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WORLD'S LARGEST INDEPENDENT HAM MAGAZINE 






$1.00 

EMPHASIS: 

MOBILE OPERATION 



No. 116 



Features 



FCC: 

REPEATER DOCKET 

(WITH COMMENTS) 
page 20 

4-LETTER WORDS 
page 2 



ACTUAL 
SIZE 




* 



MICROMX N 1 AT U^fc. 



T 




f A 



VwC ■ ■ ■ 



E STAMP TRANSMITTER . . . page 80 



■ 



11 



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SSB, 360 watts CW! 550 
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sensitivity, amazingly high 
stability. 

*550 00 






The FM-21 0. "Hottest Value" 
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143-149 MHz frequency 
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Write for free brochures. Just tell us your 
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10 South 34th Street • Dept. 73-KK53 • Council Bluffs, Iowa 










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# 116 May, 1970 
Features 

2 Radio Amateur News Page 
8 Caveat Emptor 
10 Never Say Die 
14 Mr. Virgo Himself 
16 Leaky Lines 
131 New Products 
136 Letters 
144 Propagation Chart 
144 Advertisers Index 

Readers' Double Bonus 

STAFF 

Editor-Publisher 
Wayne Green W2NSD/1 

Managing Editor 

Ken Sessions K6MVH/1 

Advertising Manager 

Diane Shaw 

Art Director 

Roger Block 

Graphic Arts 

Jeanne Caskie 
Nancy Estte 
Bruce Marshall 

Composition 

Jane Tracey 
Joan Bernier 

Drafting 

Wayne Peeler K4MVW 

Bill Morello 

Gary AudissWA6EPN 

Production 
Phil Price 
Judy Marcus 
Lloyd Carren 
Richard Marcus 

Subscriptions 
Dorothy Gibson 

Circulation 

Jon Fisher 

Comptroller 
Joe LaVigne 

Propagation 
John Nelson 

WTW Editor 

Dave Mann K2AGZ 

FCC Liaison 

Bob Nelson WA5MAM/4 



Contents 

73 Comments on FCC's Proposed Repeater Rules ..... .Staff 

Passage as proposed could be catastrophic. 

What Will Become of CW? W5TOM 

What became of the passenger pigeon? 

FM— AM Transmitter— Receiver Aligner W3JKL 

Two transistors, any band HF or VHF, simple, useful. 

5/8 Wavelength Verticals WAONGV 

Twice as good as a quarter-wave. 

The Intelligent Use of Two Meters FM K1ZJH 

It is possible. 

. . .piUS IU UD • f t ■ t < • ' •••••■• iVtWLU 

The October '68 article was better illustrated. 
A Ham-Style Burglar Alarm for the Car . . , K2JLD 

First take two sticks of dynamite, then. . . 
Power Supplies From Surplus Components . , , . WB6BIH 

Cheapskates' power supply manual 

RF, Riviera Style . . K9BDJ 

Quieting Buick's super noise generator. 

Keep 'em Cool In KPO Cans * .G3KPO 

Cheaper than blowing your cool. 

Towards The Ideal Solid-State l-F K1CLL 

Part II - Filter, Converter, AVC 

State-of-the-art for VHF. 
Epoxies for Electronics * ,,....... .W9KXJ 

Cold solder joints become respectable at last. 
FET Preamplifiers For VHF Operation WA4WDK 

20 dB gain =100 times the power! 

Educated Idiot Lights D J. Holford 

Like the oil light indicating your engine just burned out. 

Postage Stamp Transmitter for Six K1CLL 

Shades of Dick Tracy, 
Getting Your Extra Class License, Part XVI , . .Staff 

RF power amplifiers. 
The 27 -Minute Mobile Noise Limiter W7SOH 

If you build it right, it may last even longer. 
A Low Band Police Monitor . * W6JTT 

For emergency, CD, or SDS use, 

A Mobile CW Transmitter , - - - W6BLZ 

Gives a driver something to do with his two free hands. 

An FM "Best Buy" , . . WA7EMM 

You have an FM editor and you have FM articles. 

Science Fairs: Science Education Staff 

By the Science Editor of Radio Today. 

The Wichita Autopatch • .*.**.«,**•« W0DKU 

Telephone through a 2m FM repeater (while you still can). 
London's Science Museum Demonstration Station. • * . « Ellison 

GB2SM. 
Try Bigger Knobs For Better Operating Performance .WB2ICV 
Tiny knobs cramp your style. . .and fingers. 



73 Magazine is published by 73, Inc., Peterborough, New Hampshire 03458, 
Subscription rate- $12.00 for three years, $6 00 for one yean Second 
Class Postage paid at Peterborough, Sew Hampshire, and at additional 
mailing offices. Printed at Pontiac. Illinois, U.S.A. Entire contents copy- 
right 1970 by 73, inc., Peterborough, Sew Hampshire 03458. 



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116 
118 

125 



MAY 1970 



1 



Amairar 




News fagr 



May XIXLXX 



Monthly Ham News of the World 



73 Magazine 



FCC SAYS 



I he FCC questioned CBVr Richard 
Tallnum f $ qualifications to hold a 
Te c h n i e i a n -c I ass amateur license 
been use of his prior violations of rules 
pertaining to: (1) hobby-type use of 
his CB station, (2) failure to identify 

his station properly, and (3) transmis- 
sion ol* ^allegedly obscene, indecent, or 
profane language, words, or meaning/' 
In scheduling a hearing for the case, 
the constitutional issues raised by the 
FCC's rule against profanity were 
noted by Commissioner Nicholas John- 
son, 

Johnson concurred that a hearing 
should be held to determine the appli- 
cant's qualifications to become a ham, 
but he emphasized that the "pro- 
f'.uiiiy" issue should be dismissed. "I 
believe a license renewal hearing on the 
basis of the first two alleged violations 
is clearly warranted/* he said; but then 
he added, ". ( .when we revoke licenses 
fur the content of the speech. , .we 
enter an area of constitutional law 
which is hedged with important re- 
straints against the power of govern* 
menl to curtail freedom of speech/* 
Because of a recent supreme court 
decision involving the impact of the 
First Amendment on broadcasting, 
Johnson said, the Federal Communica- 
tions Commission cannot punish -"by 
fine, license revocation, one-year re- 





ARE 




NO'S 



_ i I 



i' 




"Agh! By golly - by golly? 



*r 



Vagueness and 'overbreadth/ See, e.g., 
Zwickler v. Koala* 389 VS. 241, 249 
( 1967); Columbia Broadcasting System 
(WBBM^TV). IK KCC 2d 124, 143, 
ISO (1969) (dissenting opinion). It 
might easily constitute a prohibited 
'establishment of religion 1 as well/ 1 

"Webster's Dictionary defines the 
word, Indecent/ as 'not proper and 
fitting; unseemly; improper/ or 'moral- 
ly offensive; immodest; obscene/ 
Again, unless 'indecent' is narrowly 
limited to the .technical definition of 



Ham Wins Test Case 

A Chesapeake, Virginia ordinance 
against transmitters and towers was 
defeated in the courts recently by Gay 
Milius W4NJI , who was acting as 
attorney for Ted Anthony K40QB, in 
a civil case thai tested the legality of 
the regulations. 

Tri-State Hamfest 

by WA9WCE 

The Tri-Slale Amateur Radio 
Society is holding its twenty-third 
annual hamfest on Sunday. July 12, 
1970, ai the 4 II Rural Youth Center 
on Highway 41 North, Evansville, IN. 
Advance registration SL50;and S2.00 
at the door. For details contact Jack 
Young K9LAU, Box 492, Evansville, 
IN 47703- 

British Carnival 

Rally 

by Q3B1D 

By permission of the United States 
Third Air Force, the Amateur Radio 
Mobile Society wilt be holding a carni- 
val rally on 5 July 1 970 at Alconbury, 

United States Air force Rase in 



Cook 
Bicentenary 

Award 



The Wireless Institute of Australia 
has a nice certificate available for 
anyone contacting fifty AX stations 
during 1970, Send a list of the stations 
you have contacted in order of call 
signs by call areas plus the date, time 
(GMT), band, mode, and report for 
each contact. Have this list certified by 
two other licensed amateurs plus a 
statement to the effect that they have 
seen the entries in your log. Send your 
application (no QSl/s) to Awards Man- 
ager WIA, Box 67, East Melbourne, 
Via, 3002, Australia, Add eight IRC's 
if you would like the certificate by 
airmail. 



Western Illinois Hum lest 

The Western Illinois Amateur Radio 
Club is holding its 10th Annual Ham- 
fest on June 7th, 1970, at the Adams 

County Fairgrounds located North and 



newai or other sanction**— a licensee 
"for speech which is protected by the 
first Amendment." 

In his in-depth statement (pub- 
lished by the FCC us an appendix to 
Docket 18804), Commissioner John- 
son gave detailed reasoning behind Ins 
controversial stand: 

"The Commission has promulgated 
guidelines for forbidden speech in Rule 
95.83 (a) (3)- The Rule's prohibitions 
of "obscene, indecent or profane lan- 
guage, words or meaning" are appar- 
ently taken from 18 U.S.C. § 1464. 
I ach of the three elements in Rule 
95,83 (a) (3) warrants consideration, 
lor I urn increasingly of the belief thai 
one or more of them are unconstitu- 
tional abridgements of the freedom of 

speech. 

"The concept of "obscenity' lias 
been defined by the Supreme Court in 
the famous case. Memoirs v. Massachu- 
setts* 383 U.S. 413,419 (1965 h The 
Court has not, however, to my know- 
ledge, ever said that particular words 
arc *obsene' per se. On the contrary, 
i he Court lias always stressed the con- 
text in which the words appeared, 
asking whether the dominant theme of 
the material 'taken as a whole* appeals 
'to a prurient interest in sex.' Indi- 
vidual 'four-letter words/ so-called, 
may arouse a number of emotions in 
the listener; but I rather doubt that a 
'prurient interest in sex* is one of 
them. Presumably the hearing exam- 
iner in this case will address this 
question - along with such other con- 
stitutionally required questions as 
whether Mr. Tall man's speech was 
* utterly without redeeming social 
value/ A study of the function of 
fc fdttr-letter words' in our society, for 
example, might be useful, or necessary, 
component of this latter inquiry, "pro- - 
fane' as 'showing disregard or con- 
tempt for sacred things: ir reverent, 1 
Any attempt by this Commission to 
punish for 'contemptuous' or irrever- 
ent* speech would almost certainly* in 
my mind, suffer from unconstitutional 



-Obscenity/ there is little doubt in my 
mind that its breadth and vagueness 
make it unconstitutional. In Interstate 
Circuit, Inc, v. Dallas, 390 U.S. 676 
(1968), lor example, the supreme 
court cited with approval an earlier 
case. Hoimhy Product fons, inc. v. 
Vaughn, 350 U.S, 870 (1954), which 
declared unconstitutional a statute 
containing the words, 'cruel, obscene, 
indecent, or immoral.' And just last 
year in Williams v. District of Colum- 
bia. No. 20, 927 (D. C. Cir., June 20, 
1969) (en banc), the United States 
Court of Appeals threw out a statute 
with wording almost identical to Com- 
mission Rule 95.83 (a) (3), The invali- 
dated District of Columbia statute also 
contained the words, \ , .profane lan- 
guage, or indecent or obscene words, 1 
"My essential point is that this 
Commission has designated a license 
renewal application for hearing pur- 
suant, in part, to Commission rules 
which appear unconstitutional on their 
face, I am concerned that the Commis- 
sion takes this step without attempting 

to formulate precise standards for 

permissible speech over the broadcast 
medium assuming any t such stan- 
dards could withstand constitutional 
scrutiny. 1 concur in today's action, 
however, solely because grounds exist 
for possible license revocation which 
are completely independent of the 
allegations raised under Rule 95.83 (a) 
(3), and because the Commission will 
have the opportunity at a later date to 
review the policy and law in this 
difficult area. 



ii 



Slow-Scan Hams 
Active Worldwide 

by WA7LQO 

A world-wide slow-scan TV net has 
been meeting between 1800 and 2000 
GMT weekdays. Stations in Alaska, 
Belgium, Sweden, U.S.S.R., Italy, as 
well as the U.S. and Canada have been 
sending pictures, 



Huntingdonshire, England* 

Any inquiries regarding the rally or 
regarding reciprocal licensing arrange- 
ments should be addressed to: 

BCM/ARMS, London, W.C.I. 

Application forms for British 
reciprocal licenses can be obtained 
from: 

Ministry of Posts and 

Telecommunications, 
I elecommimications and Radio 

Regulatory Division 
Amateur& Special Licensing Branch 
Waterloo Bridge House 
Waterloo Road, London, S.E. 1, 

The cost is £3 Tor a fixed license or 
El. 10 Od. for a Mobile License. Ama- 
teurs can apply for both, or either, but 
a separate mobile license is necessary in 
Britain for mobile operation. 




1970 Ham-of-the-Year Ajward 

The Federation of Eastern Massa- 
chusetts Amateur Radio Associations is 
now requesting nominations for the 
'Ham of the Year" award for 1970. 
Only amateurs in the first call district 
are eligible and the ham selected will 
be the top "good neighbor" among 
iums - the one who has performed an 
outstanding public service. 

Anyone tnay nominate a ham for 
the honor. Winner of the award will be 
chosen for the ham activity which 
brings the greatest benefit to an indi- 
vidual or group and for the amount of 
ingenuity and personal sacrifice dis- 
played in performing the service. 

Nominating tetters should include 
the candidate's name, address, call let- 
ters and complete description of the 
service performed, Letters must be sent 
to the chairman of the FEMARA 
awards committee, Eli Nannis WHIKG, 
37 Lowell St. Maiden, Mass. 02148 
before September 1. 1970. 

The winner will be oresented with a 
plaque and a cash award at the ARRL 
National Convention, Statlcr-Hilton 
Hotel, Boston, Mass. on September 26, 
1970. 



Last of Qtlilicy, Illinois. 

Calling frequencies will he 3.910 
Mil/. 7,258 MHz (Mid Cars) 146.94 
MHz and 146.34 MHz 2 meter I'M 
Repeater. 

Swap-shop, prizes, games, lunch. 
ALL-COVERED I ACUITIES. Event 
will be held rain or shine. Camping 
facilities are available on the fair- 
grounds* 

Tor further info contact WA9ARG, 
Marshall Coins, 2316 Van Buren St,, 
Quincy, i||. 62301. 

SYRIAN MARATHON 
OPERATION PLANNED 




Rasheed YK1AA and Hikman 
YK1 AM are planning a round-the-clock 
three week operation for October 
1970, with extensive friday operations 
from then on through February 1971. 
The details of equipment are being 
worked out with Stu Meyer W2GHK/4 
(DXpedition of the Month) and they 
should be on all bands with good 
signals. This ambitious operation 
should take Syria off the rare list for a 
long time to come. All it lakes is one 
good effort like this to do it. 

A copy of the 73 l)X Handbook 
has been sent to Rasheed so he will 
have information on how to best 
handle the pileups of stations calling, 
Using the techniques described in this 
book he and Hikrnat should be able to 
contact three to five a minute, even 
when their signals may not be too 
strong. 









FCC Proposal 
Shoot Down Ham 





The proposed Docket 18803 for 
regulating amateur repeaters has a seri- 
ous hooker in it. - .a proposal thai 
repeaters nol bo permitted to repeal 
other repeaters. If this gets passed, 
then a set of synchronous satellites for 
450 MM/ k out the window. Ibis 
could be the most severely restrictive 
legislation yet for the future of ama- 
teur radio. 

The rapid development of FM re- 
peaters plus the amateur satellites 
means that the time is not fur off when 
we can put a series of three synchro- 
nous satellites in orbit which will per- 
mit any amateur in the world to 



contact any other on 450 MHz, 
Imagine what a change that will make 
in our hobby! Armchair copy signals 
without QRM from anywhere in the 
world. This could be the biggest step 
ahead for the hobby since its incep- 
tion, - .if 18803 does not go through as 
proposed. 

Rear back and fight this one out. 
Send in your comments, . .get your 
club to comment, . .your friends, , .the 
fellows on the air* • .leave no stone 
unturned. Get your congressman to 
complain about this. . .your senator. 
get Barry Goldwater to help kill this 
provision. . .maybe even the ARRL. 



Penn- Central 
Ham f est 

by W3GPR 

The seventh annual Pehn-CentraJ 
Manifest by the Wilhamsport and 

Milton clubs will be held Sunday, June 
7, 1 970 starting at 12:00 noon at the 
Union Township Volunteer Fire 
Grounds on Route 15, Win field, Penna.- 
Informal, picnic style, snack bar handy 
<>i bring your own lunch - come and 
go as you please. Auction, contests. 
swapping, free parking, with both 
indoor and outdoor facilities provided. 
A $2.00 registration fee may be paid at 
the gate. XYL and children admitted 
free. Exhibits welcome. For infor- 
mation contact Al Schramm, 311 E. 
Mouniain Avenue, South Williamsport, 
Penna- Phone - 717-323-5576, 



1970 ARMED FORCES DAY COMMUNICATION TESTS 



Each year on the third Saturday in 
May, the Department of Defense spon- 
sors the observance of Armed Forces 
Day- As a part of this observance the 
Departments of the Army, Navy and 
Air Force annually conduct communi- 
cation tests designed to demonstrate to 
the world the close partnership and 
mutual respect enjoyed between U. S. 
amateur radio operators and the U. S, 
mill tar v. This year's program will be 
conducted on Saturday, May 16, 1970, 
and all licensed radio amateurs are 
encouraged to participate. 

The radio amateur's contributions 
to communication training, inter- 
national goodwill, military morale and 
emergency services are recognized by 
every echelon of the military services. 
The Armed horces Day communica- 
tion tests are designed to be a tangible 
demonstration ot the firm and long- 
standing Department of Defense policy 
to encourage and support amateur 



STATION 



MILITARY 

FREQUENCY 



radio activity. On this twenty-first 
observance of Armed Forces Day, all 
radio amateurs are invited to partici- 
pate and demonstrate to the world the 
close partnership and mutual respect 
that LL S, amateurs and U. S. military 
enjoy. 

Once again this year, several mili- 
tary radio stations will participate in 
communication testi wnich include 
military-to-amateur crossband oper- 
ations and receiving contests for both 
CW and RTTY modes of operation, 

Special QSL cards confirming cross- 
band communications will be for- 
warded to those amateurs who estab- 
lish two-way contact with participating 
military stations, Certificates will be 
awarded to those who aptly demon- 
strate their operating ability and tech- 
nical skill by receiving a perfect copy 
of the Secretary-of-Defense-originatecl 
CW or RTTY message transmitted dur- 

APPROPEIATE 
EMISSION AMATEUR BAND 

(MHz) 



mg the receiving contest portion of the 

communication tests. 

Military to Amateur Crossband Test 

Military radio stations WAR, NSS, 
NPG and ATR will be on the air from 
16/1400 GMT to 17/0245 GMT, Dur- 
ing this test of crossband operations, 
the military stations will transmit on 
specified military frequencies while 
amateur stations will transmit in the 
indicated portions of the amateur 
bands. Contacts will consist of a brief 
exchange of locations and signal re- 
ports. No traffic handling will be per- 
mitted * 

CW Receiving Contest 

A "CW" receiving contest will be 
conducted for any person capable of 
copying International Morse Code at 
25 words per minute. The "CW" 
broadcast will consist of a special 
Armed Forces Day message from the 
Secretary of Defense add) d to all 
radio amateurs and other participants. 
The schedule for this broadcast is as 
follows: 

TRANS. I KEQ 

IIMfc STATIC <KH 



News, Reviews, 
Announcements 



IOWA PICNIC 

by W0RJZ 

Th€ Iowa 75 meter phone net 
annual panic will be held on I he 
second Sunday in August August 9 $ 
197(1 al Anson Parkin Marshalltown, 
Iowa. All amateurs and their families 
are cordially invited- Each should bring 
a covered dish and his own service. 
Festivities will begin around noon. 
Prizes will be offered and a swap tabic 
will be available. 

Floridafest 

The ST. PETERSBURG AMA- 
TEUR RADIO CLUB, INC. will hold 
its annual Manifest at Lake Maggiore 
Park, entrance gate at 9th Street South 

and 38th Avenue, St. Petersburg* 

Florida, Sunday May 17. All hams and 
guests cordially invited. This is an 
oldfashjoncd hamfest with picnic 
lunch, swap table and prizes, 

OLDOLDTIMERSGETNEW 

OFFICERS 

Andrew L. Shafer W8TE is the new 
president o( the Old Old Timers' Club, 
Inc. with William B. Gould K2NP as 
the new Vice President, 

Ray Meyers W6MLZ has been ap- 
pointed T xccutive Secretary-Treasurer 
and Editor of "Spark Gap Times" 
official magazine for the OOTC\ 

Directors serving the ten U.S. Call 
Areas are: 

District 

Walters. Rogers WIDFS 1 

William B Gould K2NP 2 




kHz unless 
otherwise noted 



WAR (Army 


4001.5 


CW 


Kadin, Wash., 


4020 


CW 


D.C.) 


8992,5 


CW 




7325 


CW 




14405 


CW 


NSS (Naval 


*3385 


CW 


Communication 


4012.5 


RATT 


Station, Wash,, 


*4040 


LSB 


D.C.) 


G970 


LSB 




**730l 


CW 




**7336 


LSB 




7380 


RATT 




7385 


CW 




13940 


RATT 




14385 


USB 




14400 


CW 




21500 


CW 




***49.692 MHz 


AM 




***143,820 MHz 


AM 




** *1 50.090 MHz 


FM 



'To be operated from 16/2200 
GMT to 17/0245 GMT. 

**To be operated from 16/1400 
GMT to 1672200 GMT. 

***Provided it is consistent with oper- 
ational and training commitments, 
this frequency will be keyed from a 
U.S. Navy aircraft flying between 
Washington* D. C, and Brunswick, 



^Provided it is consistent with oper- 
ational and training commitments, this 
frequency will be keyed from a U.S. 
Navy aircraft flving between San 
Diego, California, and Seattle, Washing- 
ton during the major portion of the 



3,5 - 3.65 
3.65 - 3.8 
7,0-7.1 
7.1 -7.2 
14.0- 14,2 



J » <3 - o 

3.65 - 

3,8 - 4 

7.2 - 7 

7,1 -7 

7.25 

7.0 - 

7,0- 

14,0 

14,2- 

14.0- 

21.0- 

50.1 - 

144.0 

144.0 



7 
7 



,65 

3,8 

,0 

.25 

.2 

7,3 

.2 

.1 

14.1 

14*35 

14.2 

21.25 

54.0 

- 145.5 

- 147.9 



NPG (Naval Com- 


4001.5 


LSB 


munication Sta- 


4005 


CW 


tion, San Fran- 


4016,5 


RATT 


cisco, Calif.) 


7301.5 


LSB 




7347.5 


RATT 




7365 


CW 




7495 


CW 




13922.5 


RATT 




13975.5 


CW 




14356 


USB 




14375 


CW 




20954.5 


CW 




21600 


USB 




#143.700 


AM 




##148.410 


FM 


AIR (Air Force 
Radio, Wash,, 


3347 


CW . 


4025 


LSB 


D.C.) 


6997.5 


CW 




7305 


LSB 




7315 


RATT 




13995 


CW 




14397 


USB 




20994 


CW 



Maine, between 16/1200 GMT and 
16/1430 GMT. The aircraft will 
depart Brunswick, Maine at 
16/1730 GMT and fly westerly to 
Akron, Ohio, Southerly to Morgati- 
townj West Virginia, and return to 
Washington, D, C, at approxi- 
mately 16/2100 GMT. The call sign 
NSSAM will be utilized from the 
aircraft. 



3.8 - 4.0 
3*5 - 3.65 
3,65 - 3.8 
7,2 -7.3 
7,0-7.2 
7.0 -7.J 

7.1 - 7.2 

14.0 - 14.1 
14.0- 14.1 
14.2- 14,35 

14.1 - 14.2 
21.0-21.25 
21,25 - 21.45 
144 - 148 
144 - 148 

i J , O " J . O 

3.8 - 4.0 
7.0 -7.2 

7.2 -7.3 
7.0 -7.2 
14.0- 14.2 

14.2 - 14.35 
21.0- 21.1 

time allotted for military to amateur 
Crossband contacts. The call sign 
NPGAM will be utilized on the aircraft. 

##To be operated from Mt. Diablo 



16 May 1970 

l7/n,Hioi,ui war Army 



16/2300 HOST NSS N»*y 
16/2000 PPM HVi; Navy 



.1347.6992.5. 
14405 

UH5. 7585, 14400, 
21500 

4(1(15,7445. 1WS,5, 
20954,5 

AIR AirHiuc B97.5 t 7315, 13995 

A h USA Army 6997.5 
K lid 10 S,m 
I nm eisco 

RTTY Receiving Contest 

A radio teletypewriter receiving con- 
test will be conducted for any indi- 
vidual amateur or station possessing 
the required equipment. This is a test 
of the operators technical skill in 
aligning and adjusting his equipment, 
and serves to demonstrate the growing 
numbn ol" amateurs becoming skilled 
in this method of rapid communica- 
tions. The "RTTY* 1 broadcast will 
consisl of a special Armed Forces Day 
message Trom the Secretary of De- 
fense to all radioteletypewriter enthu- 
siasts. The message will be transmitted 
at 60 words per minute in accordance 
with the following schedule: 

TRANS. FREQ. 

TIME STATION (kHz) 

16 May 1970 

17/0335 GMT WAR Army 



16/2335 IDS I NSS Navy 
16/2035 POST NrX, Navy 



u 



3347,6992.5. 
14405 

4012*5,7380, 

1 3940 

4016,5. 7347.5. 

13922.5 

Aft USA Army 6997 + 5 
Riidiii Sill 

PrincUcc 

A5PNA Army 4U25 
Kiidio I tut 
Houston TX 

Submission of Competition Entries 
Transcriptions should be submitted 
as received." No attempt should be 
made to correct possible transmission 
errors. 

Time, frequency and call sign or the 
station copied as well as the name, call 
sign (if any) and address of the indi- 
vidual submitting the entry must be 
indicated on the page containing the 
text. Kach year a large number of 
perfect copies are received with insuf- 
ficient information, thereby precluding 
the Issuance of a certificate. 

Completed entries should be sub- 
mitted to the Armed Forces Day Con- 
test, ATTN: AKOCCOM, Room 
3E09U, James Korrestal Building, 1000 
Independence Ave,, Washington, D. C, 
20330, and postmarked no later than 

31 m.iv n*7<l 



Thomas Appleby 
Raymond I . Guy W4AZ 
Walter M. Hammond W5HN 
Robert Molly WdDKV 
Lawrence S. Linville W7DH 
Andrew L. ShaferWKTI 
G. Lane Lklrcd W9SG 
Ed. Kreeman VV0MOA 




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Military Hams to Award 
Armed Forces Day Certificates 

by WA9NV0 

On Saturday, May 16, l l )70. 
WA9DZL. amateur station of the 
128th Air Refueling Group (TAO. 
Wisconsin Air National Guard will 

place radio equipment on the hum 
hands in conjunction with Armed 
Forces Day. An attractive commemora- 
tive Armed Forces Day certificate will 
be mailed to all hams who contact 
WA9DZL on this day* The operating 
schedule is as follows: 

14.297 MHz 1300 GMT - 2100 GMT 

7.280 MHz 1300 GMT - 1730 GMT 

28.650 MHz 1 730 GMT - 2 1 00 GMT 

It is anticipated that all states and 
continents will he contacted. To qual- 
ify for a certificate, just make a two- 
way contact with WA9DZL and send 
in your QSL card to WA9DZL, I28lh 
Air Refueling Group (TAO, General 
Mitchell ANG Base. Milwaukee. Wis- 
consin 53207. 



Editorials 




DXer's Death is Loss 
To All Ham Radio 

byW.R. Lathrop W4PR 

The amateur radio fraternity lost 
one of its great citizens on March 7, 
1970 when E. C. Atkerson died unex- 
pectedly of a heart attack. Ack - 
hardy, robust, energetic - had his first 
warning last fall when he was hospital- 
ized from a serious heart attack. He 
recovered quickly, continued under 
doctors* orders, dieted, took care of 
himself, and alowcd his active business 
pace. However, there came a second 
attack on Saturday and Ack died 
instantaneously, 

Ack loved amateur radio. He began 
in 1921. He dovoted himself, over the 
years, not only to enjoying this fasci- 
nating hobby but in using his facilities 
in service to his country as well as the 
genera] public. His profound self- 
taught knowledge of electronics, for 
example, was voluntarily put to use in 
the last world war. The country then 



with a client. Yet, let a child walk in, 
whose head perhaps didn't reach far 
above the counter, one who professed 
an interest in becoming a radio ama- 
teur and Ack would "give him the 
store." Despite the rush of business, he 
would take time out - sometimes for 
hours to explain, advise, and lead the 
youngster toward his goal. More often 
than not the youngster would walk out 
with needed equipment even though tie 
did not have the money to pay for the 
items wanted. He never lost interest in 
these children, und he continued to 
help and advise throughout their ama- 
teur careers, Ack was particularly gen- 
erous in donating equipment new and 
used. He was instrumental: in providing 
most of Alabama's civil defense equip- 
ment in the early days. Since Ack 
never talked about what he did and to 
whom he sent equipment, there is no 
telling how much gear he packaged and 
sent at cost or free of charge to needy 
hams, missions, and the like. 

Ack particularly loved animals of 
all kinds. Out of hundreds of such 
stories illustrating his kindness to the 
animal kingdom, one should suffice 
which fully illustrates this trait. One 
day he found a pigeon with a broken 
wing outside his store. He personally 
took it to the veterinarian, had it 
treated, nursed and treated it back to 
health. He footed the bill and freed the 
bird on its recovery. He never spoke of 
what he had done. 

Virtually the whole DX fraternity 
knows and appreciates Ack*s interest 
and help in his efforts in this direction. 
Few know, however, of the tremen- 
dous difficulties, the sweat, the hard 
work, and file time involved in doing 
the necessary to receiving permission 
for Gus, W4BPD, to operate from the 
various exotic places that he visited. 
Nor do few know the personal 
expense, the vexation, the many prob- 
lems met and solved or of the thousand 
and one other details carried on by 
Ack in connection with Gus' travels. It 
was Ack's idea, thinking of the small 



Propagation Study Association were 
available when Don's partner, Chuck 
Swain, was lost at sea. He did much to 
keep the search going until hope was 
finally abandoned. 

Then came again a second Gus 
Browning expedition with all the work 
and effort which Ack shouldered with- 
out hesitation. These three well known 
expeditions tell part of the whole 
story. Ack's personal interest, his 
energy and drive were, however, lent to 
countless expeditions. Financial help, 
on Ack's suggestion, sometimes came 
from the World Radio Propagation 
Study Association. Ack personally con- 
tributed his own money and equip- 
ment and help in countless sorts. 

Although there is much more, let 
one more example of Ack's influence 
and interest suffice. Through a long- 
time radio communications correspon- 
dent and friend, N, Chhwana, a high 
official of the Bhutan government, Ack 
arranged to have the king invite Gus to 
visit that country. As a result of that 
visit a strong friendship was developed 
and knowing, through Gus, of the 
Bhutan's needs of radio equipment, 
Ack shipped much equipment to the 
government of Bhutan, much of it at 
his own expense. Then through per- 
sonal appeals to many radio friends 
and appeals through the World Radio 
Propagation Study Association, Ack 
collected and shipped a tremendous 
amount of radio equipment to Bhutan 
— all donated. 

Yes, amateur radio lost a devoted, 
amazingly helpful citizen when W4- 
Echo-Charlie-Ida's cheerful voice was 
silenced! We all owe him much. Truly 
Ack deserves a top spot in amateur 
radio's Hall of Fame. 



Bermuda 

Phone/CW 



change reports with U.S., Canadian and 
VP9 stations only. U.S. and Canadian 
stations may not exchange reports with 
another U.S. or Canadian station; like- 
wise U.K. stations may not exchange 
reports with other U.K. stations. 

Points 

Each contact must be complete and 
will count three points. 

Scoring 

The score for U.S., Canadian and 
U-K. stations will be the number of 
completed contacts times three points, 
times the total number of Bermuda 
Parishes worked on all five bands, i.e. a 
U.S. or Canadian station having made a 
total of 500* contacts with U.K. and 
Bermuda stations and the following 
Bermuda Parishes: 28 MHz - three 
Parishes; 21 MHz - six Parishes; 14 
MHz - three Parishes; 7 MHz - two 
Parishes; 3.5 MHz - two Parishes, the 
score would be 500 contacts times 
three points = 1,500 points times 16 
Parishes = 24,000 points final score. A 
U.K. station completing 500 contacts 
with U.S., Canadian and V P 9 stations 
would score in exactly the same man- 
ner. 
Equipment 

Any number of transmitters and 
receivers will be allowed and competi- 
tors may use the maximum power 
permitted. However, all stations parti- 
cipating must be single operator only. 

Awards 

A trophy will be presented to the 
winner of each mode. A certificate 
signed by His Excellency The Governor 
of Bermuda will be sent to the highest 
scoring station in each call area as 
follows: 

U. S. A. and Canada; Wl through 
W0 and VE1 through BE7 including 
VO, 

U. K.:G,GD, GM, etc. 

Presentations 

Round trip air transportation for 
two plus one week's accommodation at 



had need of a tremendous number of 
technicians to operate the radio gear 
used during that war. Aek volunteered 
to teach and to train technicians. He 
did so during the war period. All along 
before and after the war he used his 
facilities wherever possible for traffic 
handling. On the second Byrd expedi- 
tion to the Arctic in 1939, Aek estab- 
lished and maintained constant contact 
with the expedition. Interestingly 
enough, the expedition was ^plit into 
two camps some 1800 miles apart. 
There was an eastern location and a 
western Location and they took radio 
equipment along to maintain contact 
between the two camps. Little was 
known about propagation in the Arctic 
in those days and much to Byrd's 
dismay the contact between the two 
camps was impossible with the equip- 
ment on hand, Aek could copy, how- 
ever, both camps. He therefore linked 
the two together by maintaining twice- 
daily contact. He handled all the 
communications between the two units 
until suitable radio equipment was sent 
in. During the period of the Byrd 
expedition he handled thousands of 
personal messages from those with 
Admiral Byrd to their families through- 
out the United States. 

Again in prewar days he established 
contact with the Kenner Green scien- 
tific expedition to Peru, He was their 
main contact with the outside world 
for that expedition deep in the jungles 
of this South American country, Aek 
later rendered tremendous service to 
families throughout the United States 
when a volcano in Hawaii blew its top 
causing untold damage and destruc- 
tion, Ack's station was the principal 
radio link. 

Ack % s interest in amateur radio 
caused htm to found Aek Radio short- 
ly after the last world war. Aek was an 
alert, capable, hard working, imagina- 
tive, "tough" businessman, and Aek 
Radio grew and thrived, lie might well 
have been abrupt and business-like 



amateur without funds, who insisted 

on QSLs for everyone regardless of 
their contribution. 

The World Radio Propagation 

Study Association also was Ack's idea. 
Not unly did this organization act as a 
recipient of, and a disposal medium for 
the contributions from thousands of 
amateurs, but the analysis of Gus* logs 
and the propagation conditions per- 
taining to it were studied to provide 
benefits for amateurs the world over, 
the governments visited and various 
commercial interests. These studies 
were made and distributed. 

After Gus* first extended travels, 
the World Radio Propagation Study 
Association backed and sent Don 
Miller on a similar expedition* Aek saw 
to it that finds from the World Radio 




1BOnn DX 

by W8ANO 

During November 1 969, Stewart 
WIBB came out to the 8th district to 
see what was making all the racket on 
I Ml meters. Here is what he found: 
Three 8s very interested in 1 60 meter 
DX, I have worked the following 160m 
DX since Nov: ZS, HR3, PJ0, KP4, 
VP9, KV4, HR2, ZL1, G 3, GW3, DL9, 
KL7, G2 t G8, KS4, VK5, VOL VK3, 
KH6, 



Contest 




by Jim Sayer VP9B Y 

Bermuda hams have been active 
participants in the realm of amateur 
radio since well before the inception oi 
the Radio Society ot Bermuda in the 
late forties. Several of the old single- 
letter calls are still to be heard. In 
l l )59 t in honor of the Bermudas' 350th 
Anniversary it was decided to hold a 
contest embracing amateurs in the 
United States, Canada, and Bermuda. 
This proved to be such a resounding 
success that it was continued in I960 
and has been a yearly feature of 
hamdom since that time. 

In 1969, the lOlh anniversary of 
the contest, it was decided to celebrate 
by having a phone weekend and a CW 
weekend. This decision was met with 
equally resounding success and it was 
agreed to continue the same this year 
and to invite the IL K> amateurs to 
participate. 

Contest Period 

PHONE: 0001 G.M.T. June 20th to 
0200 G.1VLT. June 21st, 

C, W.: 0001 G.M.T. July 18th to 
0200 G.M.T, July 19th, 

Bands 

The following amateur bands will 
be used: 3.5, 7, 14, 21, and 28 MHz. 

Exchanges 

Amateurs in the U.S.,, Canada and 
the LLK, will transmit a two figure 
number representing the R S report 
plus their State, Province or County. 
CW participants will transmit a three 
figure number representing the RST 
report plus their State, Province or 
County, V P 9 stations will give R S or 
R S T reports plus Parish. 

U.S. and Canadian stations may 
exchange reports with U.K. and VP9 
stations only. U.K. stations may ex- 



The Top of the Town Hotel will be 
provided to enable the overall winners 
to attend The Radio Society of Ber- 
muda's Annual Banquet to be held on 
October 22nd to receive their awards 

Log Instructions 

Keep all times in GMT and all 
contestants to compute their own 
scores and cheek logs for duplication 
to assist the Contest Committee. Print 
name and Call on each Log. All con- 
ustants must sign a statement that the 
rules and regulations have been ob- 
served. Official Log sheets can be had 
by dropping a card to Contest Commit 
lee, Radio* Society of Bermuda, P.O. 
Box 275, Hamilton. Bermuda. 

Should there be a tied score, the 
decision of the Contest Committee will 
be final. All I ops must be received by 
the Contest Committee o\' the Radio 
Society of Bermuda NOT LATER 
THAN August 1 5 th, 1970- 

The following abbreviations of 
Parishes will be used on CW. 

SANDYS SAN. 

DEVONSHIRE DEV. 

PEMBROKE PEM. 

WARWICK WAR. 

SOUTHAMPTON SOU. 

SMITHS SMI. 

HAMILTON HAM. 

PAGE! PAG. 

ST. GEORGE GEO. 



RaRa HAMFEST 

The Rochester Amateur Radio 
Association invites you to the 1970 
Western New York Hamfest and VHP 
Conference, Organizing the Hamfest is 
an ail-year effort by a good many of 
the members of RaRa, a Rochester 
ham club. Special tables can be re- 
served for clubs and groups. Check at 
the registration desk to see where your 
group can be seated. 

An impressive program is planned 
for the occasion, and special activities 
are being scheduled for l< M enthusiasts. 




, V I. mmw * ,1? *%■■*% J J l/ itim" *V* '' H-wr ,J, HHW.W * r h 55ii»% Y+ 

Caveat Emptor?;! 




^4t #" t "**.-.j* *•■-' '-% , !n' , #" ,, *"'* T A*i 



r - - 




Price — $2 per 25 words for non- 
commercial ads; $10 pn 25 word.s for 
business ventures. No display ads or 
agency discount. Include your check 
with order* 

Deadline for ads is the 1st of the 
month two months prior tt> publica- 
tion, For example: January ,1st is the 
deadline for the March issue which will 
be mailed on the 10th of February. 

Type copy. Phrase and punctuate 
exactly as you wish it to appear. No 
all-capital ads. 

We will be the judge of suitability of 
ads. Our responsibility for errors ex- 
tends only to printing a correct ad in a 
later issue. 

For $1 extra we can maintain a reply 
box for you. 

We cannot check into each advertiser, 
so Caveat Emptor. . . 

FOR SALE; NCX-5, NCX-A, VX-501, 
NCL-2000, 20A, Bandhopper VFO, 
G-7G, 12V Supply, Hain-M Kcilor, #14 
Typing Reperf, Regency AR-KHi Air- 
craft Receiver, RCA Mark 8-10 Meter 
Transceiver* Ameco Nuvislor convert- 
ers CN-50, CN-144, PS, 14MC IF, 
Sorry no shipping. Write K3DSM Gene 
Mitchell 335 Conestoga Rd. Devon PA 
19 3 3 3. 

2 METER MOS FET PRE-AMPS 

Latest-protected Dual Gate MOS PET, 
HF-144 DGK-Kit $H.50-Wired $14.50. 
Minimum 18 dB gain. Noise figure less 
than 3 dB. Topeka FM Engineering, 
3501 Croco R<L Topeka KS 66605. 

FM RECEIVER Portable, Hcathkit, 
Tunable, Model GR-K8, Tunes from 
145 to 167 MHz, Battery operated, 
e. sensitivity and selectivity for 
monitoring local repeater outputs. Like 
new, $50. Ken Sessions KliMVH, RFD 
2, Peterborough NH 03458. 



TOUCHTONE DIAL equivalent from 
Denmark. Ten button, convertible to 
all twelve with data included. State 
color: beige or black, limited number 
green. 12 VIM' required for oscillator 
operation, glfi.00 postpaid USA. J. 
O'Brien, WB6WIM. Gti()6-5th Street, 
Rio Linda CA 95673, 

TOWER HEADQUARTERS? 12 
Brands! Heights Aluminum 35% off! 
Antennas— 20% off! Galaxy, Hammar- 
lund, G onset, SBE at discount. Cata- 
log— 20^. Brown ville Sales Co. Stanley 
WI 54768. 

40th ARRL WEST GULF DIVISION 
CONVENTION July 17, 18, 19, 
Orange, Texas. Come by car, plane, or 
boat, but come to the fun, fellowship 
and entertainment. A bargain you can't 
afford to miss. Registration $8,50. 
Orange Amateur Radio Club, Box 232, 
Orange TX 7 7b\10. 

HICKOK 61 0A TV Sweep-Marker Gen- 
erator Exc $7 5, 73 Magazines #1 thru 
Nov, '67 Perfect, Write Maurice Lin- 
denaux 2042 Druid Rd, Clearwater FL 
33516. 

FM: T43G— 1, head* mike, speaker, 
146.94 xtals, 12 volt, wide band, un- 
converted as vet; make offer! TR-108: 
$85. WA9BYR, (527 Dundee Ave., 
Barring ton IL 60010, 

CHICAGO NOVICES: complete sta- 
tion. Allied 2515, DX-40, relay, trap 
dipole, key. $110.00. Will deliver, help 
install within 50 miles. K9FRZ, 7620 
Catalpa, Chicago IL 60656. 

SELL perfect Heath-aligned SB-301. 
Will ship, $210 FOB. Wifl consider FM 
gear partial des, WBfiQVW,. Andrew 
Ellis, Box 202, Stevenson College, 

UCSC, CA 95060. 

WORLD RADIO'S used gear has trial - 
guarantee! Clrgg rccpior - $199.95; 

22>er - $12*1.95: KWM2A - $749-95; 
Swan 250C - $249.95; 350 - $289.95; 
500C - $379.95; NCX3 - $159.95; 
HW22 - $79,95; DX60 - $49.95; HT40 
- $49.95; HT44 - $149.95; SX101 - 
$159.95; HQ110A - $139.95; 2A - 
$159.95; HRO50 - Si 29.95. Free 
"blue-book* list for more* 3415 West 
Broadway, Council Bluffs I A 51501. 

HOT CARRIER DIODES: HP2800 
90</ 12/$10.00. IC's: New Fairchild 
MicroLogic (epoxy TO-5) 900. 
914,60tf. 923 90^. Motorola MC790P 
SI. 90, 20/$18.00 MC789P, MC724P 
$1.05, 10/$9.50. <M> AMP: TI 
SN72709N S2.00, H/$10.00. A U guar- 
anteed. Add postage. Write for list. 
HAL Devices, Box .'165L, Urbana IL 
61801. 



INDIANA'S MOST PROGRESSIVE 
HAMFEST Sunday, May 24, rain or 
shine. Sponsored bv Wabash Co, Ama- 
teur Radio Club. Write Bob Milling, 
700 Centennial, Wabash IN 46992. 

SWAN CYGNET 260— including micro- 
phone and mobile mount. First $325 
check gets all, William O 'Byrne, 3569 
Ft. Meade Rd., Laurel MD 20810. 
301-498-1777. 

DTL INTEGRATED CIRCUITS: Guar- 
anteed New - gates 70#, buffers 80d, 
F/F 90</, dual F/F $1.15. Add 2<h/ 
postage. Also other inexpensive parts. 
Lists & prices from Mitch-Lan Elec- 
tronics Co. Dept 270, P.O. Box 4822, 
Panorama City CA 91402. 

END CARD PROBLEMS, Frame, pro- 
tect, store or display 200 QSL's In 20 
card plastic holders for $3.00, prepaid 
and guaranteed. TEPABCO, Box 198, 

Gallatin TN. 

NOVICE CRYSTALS: 40-15M $1.33, 

80M $1,83. Free Flyer. Nat Stmnette 
Electronics, Umatilla FL 32784, 

73 IS AVAILABLE to the blind and 
physically handicapped on magnetic 
tape from: SCIENCE FOR THE 
BLIND, 221 Rock HiU Road, Bala 
Cynwyd, PA 19004, 

u TOWER HEADQUARTERS!" II 
Brands! Heights aluminum 35% off! 
Strato Crank-ups, low cost! Rotors, 
antennas and gear discounts. Phone 
patch $11,95. Catalog-20tf postage, 
Brownvllle Sales Co., Stanley wl 
54768. 

TWO REMINGTON SYNCHRO TAPE 
MACHINES for sale. Price for both 
$240, plus shipping* No instruction 
manuals. R. Lee K4BAP, 660 Poin- 
settia Ave, Titusville FL 32780. 

SELL SX-ltl, like new-$100; VFO- 
$15; CIE correspondence course-$80; 
Stancor 5VCT-60A-$20. Drewing- 
WB2SMQ, 628 Anchor Ave., Beach- 
wood NJ 08722, 

WANTED 3-1 000 Z or 4CX1000A, fil. 
xfmr. and socket. Also need 
xfmr.-3000 VDC-1A. Drewing- 
WB2SMQ, 201-349-9253, 628 Anchor 
Ave., Beachwood NJ 08722. 

WIRELESS SHOP— new and recondi- 
tioned equipment. Write, call or stop 
for free estimate. 1305 Tennessee St., 
Vallejo CA 94590 (707-643-2797). 

TOP SECRET! Classified frequencies: 
spies, NASA, military, emergency net- 
works, many morel $1.00. Electronic 
Development Incorporated, 19 IK 19th 
Street Bast, Palmetto FL 33561. 



Tristate Hamfest 

hyK9VAT 

The Western Illinois Radio Club 
composed of radio amateurs in the 
Instate area, is sponsoring a hamfest at 
the Adams County l-air Grounds. 
Mendon, Illinois on June 7, 1970. A 
fine program of an entertainment 
nature is planned for radio amateurs 
and their families. Seven-hundred 
people attended the last hamfest and 
family picnic. 

It has been more or less traditional 
at these events to give away door prizes 
as attractions to improve attendance 
and participation. In the past year 8 the 
various manufacturers and distributors 
have been very generous and gracious 
in donating an assortment of prizes 
frequently used by radio amateurs, 



Certificates... 

For the Ham Who Has Everything 

RRCC - Real Rag Chewers Club, 

This certificate is available to ama- 
teurs who furnish a signed statement 
that they have had a continuous radio 
contact lasting over six hours with one 
other amateur station. Continuous 
means just that. . .no time out for 
anything. On .your application, list 
starling and ending time and date. 
Please include $1 to cover ihe costs of 
handling and mailing. 

WAAS -Worked Almost All States. 

This certificate is available to ama- 
teurs who furnish QSL cards proving 
two-way radio contact with 49 states, 
This will greatly ease the anguish of 

not being able to get that tast stai 
Please include SI to cover costs of 
handling and mailing. 



FM MOBILE TRANSCEIVER 450 
MHz,, 2-Channel trunk mount RCA ri| 
in perfect condition. Fully duplexed 
and operating as a mobile telephone* 
Includes transmit crystals for 442.12 
and 442,05; receive crystals for 448.82 
and 448,85. Crystals are from Sentry 
and an* enclosed in ovens. Complete 
less control head and cables: $100. Will 
throw in two 4 dB Com Prod mobile 
gain antennas. Ken Sessions K6MVH/1, 
RFD2, Peterborough NH 03458. 

FM MOBILE/PORTABLE TRANS- 
CEIVER 2 meters. Varitronics 
FDFM2. Perfect for repeaters. Six 
crystal-controlled channels included: 
.34-94, .94-94. .34-.7G, .31-88, 
.22—94, .28— .76, Crystals are Inter* 
national. Includes 12V battery pack, 
mobile battery cable w/connector. 
$200. Ken Sessions KtiMVII / 1 , RFD 2, 
Peterborough NH 03458, 

FOR SALE: Heathkit DX100 (B) $55; 
Hallicrafter HT40 $45; National NC98 
RCVR $50; Homebrew 2 Watt 2 Meter 
Transceiver $25, J, Middleton, 132 
Forest Hill Road, W. Orange NJ 07052. 
WA2GVQ, 

COMPLETE SET 73's for sale & singles 
from 1961. Make offer to Art Bedter, 
535 Clyde Apt. 29, Calumet City IL 
60409. 

ELECTRONIC ORGANS Transistor- 
ized, known brand, electronic assem- 
blies, two manual spinet. $60.00 f.oJb., 
send SASE for particulars. W9YCB, 
Rural Route 2, Box 52A, Angola IN 
46703, 

MOTOROLA BRICK (H 23-DCN) with 
Nicad and case, on frequency .34 — .94 
and .94™. 94, $300. ITT SOW 12 DC 
mobile, complete with all accessories, 
less crystals, $100. Budelman 17-A 
frequency-deviation meter, crystal con- 
trolled with crystals for 146.94 and 
52,525 with manual, $75, Philip Outer, 
WA5JDZ, 9006 Crestwood, Albuquer- 
que NM 87112. 

CAPACITORS, SPRAGUE 125 uF 
460V 59tf, 40 uF 450 V 29 tf 12V 

transistor, Inverter Transformers, 670V 
@ 250 ma $3,95. Minimum Order 
$5.00. N.M.E. P.O. Box 1306, New- 
port Beach CA 92663. 

ALL MY HAM EQUIPMENT: HE 45B 
6 meter Transceiver; Eldico 2 meter 
transmitter; Navy receiver with con- 
verter; complete with power supplies; 
16 element Telerex antenna, $150,00 
complete. WB2HPS Hicksvtlle NY 
11801. 



TONE DECODERS :Touchtone-Digital 
-Burst, Solid-state, modular, plug-in 
unit, 2 x 2 x 3 in., $22.50 postpaid, 
ITT 12-button tone dial, $27.50. Write 
Digitone, Box 116, Portsmouth OH 
45305. 

SPECIAL OF THE MONTH RG 

11A/U Coaxial Cable, 1st quality. 
Brand New- 124 a foot or any length 
to 2500 feet Antennas, Inc. Dept. B, 
512 McDonald Road, Leavenworth KS 
66048. 

HOT CARRIER DIODES: New HP 
2800, 90tf 12/$ 10 pp, H A L Devices, 
Box 365L, Urbana, IL 61801. 

INTEGRATED CIRCUITS: New Fair- 
ehild Micrologic, epoxy TO-5 package, 
900 buffer, 914 gate, 604 each. 923 
J-K flip-top, 90<)( each. Guaranteed. 
Add 1 &4 postage. HAL Devices, Box 
365 L, Urbana, I L 61801, 

OP AMPS: Texas Instruments SN72 
709N (DIP) $2,00 each, 6/$10.00. Add 
postage. UAL Devices, Box 365L, 
Urbana IL 61801, 

GREENE: center dipole insulator with 
, , .or, . .without balun. . .see Novem- 
ber 73, Page 107. 

GET YOUR "FIRST!" Memorize, 
studv— M 1970 Tests- Answers" for FCC 
First Class License, plus "Self -Study 
Ability Test," Proven. $5.00. Com- 
mand, Box 26348-S, San Francisco CA 
94126, 

SRRC HAMFEST— June 7, Come to 
4-H Fairgrounds Southwest of Ottawa, 
Illinois via Route 71. For data contact 
W9MKS, RFD 1, Ogiesby IL, 

MINT COND: Apache and SB-10 SSB 
Adaptor, plus cables and mike- 
Reasonable offers considered. J. 
Weatherly K1ZYG 473 Auburn, New- 
ton MA, 

SALE— teletypes Model 15-$60; Model 
19— $90; AN/FGC-IX audio converter 
$25; Hornet TB-3B Tri-band beam 
$40; Moslcy A-92-S (2 mtr) Beam 110' 
twin lead .$15; ASAHI-PENTAX 
35mm, fl. 8 -5 5mm, f 1,8-8 5mm with 
cases $150; want Central Electronics 
20A;WA4TNW 29482. 

SWAN 240 TRANSCEIVER Swan AC 
and Mobile Power Supplies, $250. 
Excellent condition, David D. Kauf- 
man, 9458 Loch Avon Dr. Pico Rivera 
CA 90660. 

FOR SALE: Heathkit Mohawk receiver 
$100, DX-60 $50, and HG-10 $25, or 
$150 for all FOB Bakersfield CA. John 
Parker 5008 Greenbrier Ave. Bakers- 
field CA 93306, 



TRANSISTOR PROJECTS: send for 
free list. EDI, 19 18 A 49th E. Palmetto 
FL 33561. 

LIN AMP for Swan 250 with two 4 x 
150 Complete Power Supply, instruc- 
tions, etc. $125.00 WA0NAO, 7 393 
Flora, Maplewood MO 63143. 

SWAN 250 complete with SKR-PS 
instructions, etc. $200.00 WA0NAO, 
7393 Flora, Maplewood MO 63143. 

430 MC RECEIVER or transceiver 
wanted, super eg preferred home made 
or rafg. Give price if in working order. 
Box 8352, Savanna GA 31402, 

10 FOOT PARABOLIC DISHES- 
Spun Aluminum. Some in original 
crates. Frequency range 450 MHz to 
8.5 GHz, No feeds available. Feeds 
available from the manufacturer or can 
be fabricated. $100. FOB Topeka FM 
Engineering, 3501 Croco Rd. Topeka 
KS 66605. 

SOMERSET COUNTY HAMFEST The 
5th SCARC Annual Hamfest will be 
held Sunday June 7 at the Casebeer 
Grove 4 miles north of Somerset, Pa. 
on US Route 219. Registration starts 
at noon. Rain or shine — Free tables 
indoors for swap-shop. Write K3YVS, 
719 Division Street, Berlin PA 15530. 

ROCHESTER, N.Y, is the location for 
the 37th Annual Western New York 
Hamfest and VHF Conference, the 
weekend of May lf»th. Location is 
Bristol 50 Acres, Rte, 15 just south of 
Thruway Exit 46. Advance registration 
and banquet only $6.75. Advance sale 
closes May 9th> Send check to Western 
New York Hamfest, Box 1388, 
Rochester, N.Y, 14603. Activities start 
Friday night followed by full day of 
technical programming with outstand- 
ing speakers. Special activities include 
MARS, AREC, and QCWA meetings, 
YL program, code contests and huge 
flea market. 

AUDIO BANDPASS FILTERS for 

improved receiving or phone patch. 
Top grade commercial units made by 
Stancor and UTC. Sharp cutoff below 
300 Hz and above 3000 Hz, 600 Ohms 
in, 10K out, use them back to back for 
even better resiilts or impedance 
match. 20 watts max. Postpaid 2 for 
$5.00. Charter Electronics Box 88, 
Gladwin MI 48624. 

PRECISION TOROIDS, wound to mil 

spec on high grade tape cores. \V% in. 
dia. not potted. Choice of 250, 500, 
850, or 1000 MHy, $1.00 each or 6/$5 
postpaid. Charter Electronics, Box 88, 
Gladwin MI 48624. 



CHC — Certificate Haters Club. 

This certificate is available to any 
amateur who sends a statement saying 
thai he has never enjoyed receiving a 
certificate, that he hates certificates, 
and that should he ever by chance 
receive a certificate in the future he 
will hate it. Please include SI to cover 
handling and mailing costs. 

DXDC - DX Decade Club, 

One hundred countries is a bit 
much for Novices, on six meters, on 
160 meters, and other esoteric bands, 
so we have this certificate available for 
any amateur who furnishes QSLs 
proving contact with ten countries on 
the official WTW country list. A dollar 
bill should cover costs admirably. 

WAZP -Worked All Zones Promised 

Though interest in the Worked AH 
Zones certificate lias dwindled substan- 
tially in recent years, every now and 
Mien a DXer comes along who wants to 
try for this award. A statement to the 
effect that you promise to try and 
work all 40 zones plus $1 for handling 
and mailing will bring you this hand- 
some certificate. 

Who will be the first amateur to 
win all five of these handsome awards? 



MAGAZINE 
PETERBOROUGH 
N,H, 03458 



STATION CLEANING-Sell six'er 
with P,T.T, $45, 1-400 $20, 4-250 
$16, much more. Send S.A.S.E. for big 
list. S Barry Ave. Bay Ridge MD 
21403. 

MANUALS— TS-173/UR, TS-174/U, 
SP-600-JX, $5.50 each; R-390/URR, 
R-390A/URR, $6.50 each. Many 
others. List 204- Manuals wanted. S, 
Cunsalvo, 4905 Roanne Drive, Wash- 
ington DC 20021. 

RTTY GEAR FOR SALE. List issued 
monthly, 88 or 44 MHy torroids 5 for 
$2,50 postpaid. Elliott Buchanan & 
Associates, Inc., 1067 Mandana Blvd., 
Oakland CA 94610. 









FCC Figures Revisited 

A little over a year ago (February and March 
1969) I gave the graphs of the FCC figures 
on the total number of amateur licensees and the 
f \lra and Advanced class licensees. At that Lime, 
with Incentive Licensing just a lew months old, it 
was obvious that there was an increase in the 
Extra and Advanced class licenses, but w£ 
eouldnU tell whether it was the start of an 
upward curve or not. The start was certain!} 
extremely disappointing to anyone that expected 
some response from the amateurs to the new 
Incentive Licensing rules. 

We have had an awful lot of talk about 
Incentive Licensing, but what is really hap- 
pening? What has been the result of the Novem- 
ber 1968 and November 1969 band changes as 
far as upgrading of licenses is concerned. . .and 
that is supposed to be what this is all about, is it 
nut? 

The figures in early 1969 seemed to indicate a 
niassive rejection of the entire principle of 
Incentive Licensing, Beyond the oldtimers who 
were grandfathered into the Extra class license, 
only a handful bothered to go for Extra. . .or at 
\i\i\\ only a handful nude it. 

Now that the figures are in through February 
1970, what do they show? Has that handful 
become a mob going for Extra? Were those few 
stragglers who went for the Advanced class 
license the forerunners of a horde to come? Is the 
principle of Incentive Licensing finally being 
accepted by the rank and file? Has QST managed 
to get this bitter pill ^wallowed? 

Not exactly. 

During February 1970 the FCC issued exactly 
73 Extra class licenses. This compares with 278 
the previous February. Perhaps this February was 
somehow different from last February. . .snow or 
something* . .SO let's take an average of five 
months and see how that compares with a year 
ago. The average, centered on January "1969 
(October through February) is 107 Extra class 
licenses a month. The year before it was 226, 
over double! 

No wonder the FCC stopped the expansion of 
the Extra class CW bands! 

What about the Advanced class license? Is 
that where the action is? 

Not exactly. In the five months centered on 
December 1968 an average of 759 Advanced class 



EDITORIAL BYWA YNE GREEN 

licenses were issued. In May 1969 the average was 
down to 329. less than half! It has not picked up 
substantially since then. The February 1970 
figure was under 40th 

This should tend to cool off those enthusiasts 
who have been talking wishfully about the 
acceptance of Incentive Licensing. It has not 
been accepted. It has been rejected. Let's not let 
anyone try to fool us about this. Perhaps, now 
that the vote is in where it really shows, we can 
prod the 1 CC into some action to get things back 
where they were before and set up a more 
realistic program for encouraging amateurs to 
progress. The punishment type of incentive as 
proposed by the ARRL and put into law by the 
I CC under pressure from ARRL has been the 
biggest trauma ever to hit our hobby. Psycho- 
logically it was doomed to failure from the 
start . .punishment" as a means for forcing action 
never succeeds like rewards. 

Perhaps it is about time to go back and do 
what should have been done in the first place. . « 
msutl the amateurs as to what they think 
should be done. Few amateurs arc not in 
reement that we need some incentives to urge 
us to progress. Maybe it is time for the active 
amateurs to take a hand in their future instead of 
leaving it to a small unchosen few r who have had 
little active ham experience in years to make the 
decisions for us from their ivory towers. 

What can be done? Well, since you have no 
representation or lobby in Washington to speak 
for you. you have to speak for yourself. Gel your 
club to send a petition to the FCC requesting a 
halt to the Incentive Licensing band allocations 
. . .get the in back where they were in October 
1968. Get as many members to sign this petition 
as you can and send it to the FCC. Be sure to 
double-space it when it is typed up and don't 
forget the lousy 14 copies (plus the original). 
You might make a 15th for me. . .and a 1 6th for 
QST. Have the original notarized and send the 
works to the Secretary of the FCC Washington, 
DX\ 

Once we get hack where we were before this 
big ARRL production, we can start working on a 
reasonable incentive system that will reward 
instead of punish. 

The FCC figures put the lie to ARRL \ 
insistence that everything is really all okav and 

- — -■ 



10 



73 MAGAZINE 




that most amateurs are accepting Incentive Licen- 
sing with good grace and getting their higher 
grade license. They have tried to maintain the 
fiction that the opposition to this was by a 
handful of malcontents and rabblerousers, 73 
Ixtra class licenses in February out of a pool of 
130,000 General and Conditional licensees tells 
the story. 

Bright Side. The total number of amateurs, 
which virtually stopped growing in 1963 <the 
time of the ARRL Incentive Licensing proposal L 
has been edging upward again. In 1967 it was 
down 2 , in 1968 it swung positive to about 
0.01%, in I9f)9 it was up to 0.5 growth, and in 
1970 it is up to 2.4 I This is not up to the 
10-12- : of the pre-1963 growth, but it is 
certainly encouraging. 

FCC Railroading Fee Hike 

The FCC announcement of the proposed 

license fee hikes readied 73 after the April issue 
had already gone to press. We did manage' to 
i|uickly insert a little bit about it gleaned from a 
phone call, but not nearly enough to make it 
possible for amateurs to be fully informed and 
comment intelligently on the docket. The closing 
date for comments was set for April 10th, 
meaning that by the time we could present the 
entire docket in the May issue, the official 
deadline for comments would be long gone. I 
immediately sent in a petition to extend the 
closing date and it was quickly denied, for sonic 
reason the FCC wants this one to go through 
with as little opportunity for the amateurs to 
know what is happening as possible* 

Docket I K8Q2 proposes that the amateur 
radio license fees be increased from S4 to $9. The 
basic idea is to put the FCC on a cash basis, 
paying its way with license fees, While I like the 
idea of a government agency operating in the 
black, I am about as anxious to help pay for 
much of the FCC doings as I am to pay for that 
love I v war in Vietnam- 

■ 

I can see where it might cost around $4 for 

the FCC to make up, print, administer, grade, 
und process a license application and issue the 
license, but I can't see it costing S9, even 
considering the inefficiency and waste of the 
government running the program instead of our 
ham clubs. 

The $9 bite wouldn't be so bad for the older 
amateurs, fellows who are working and making a 
living, but it could be a severe blow for the young 
kids in school and could even prevent many of 
them from applying for a license. Since most 
fellows fail the exam the first time through, the 
bill would run a lot higher than $9. I seem to 
remember an FCC release which mentioned that 
it takes 2% tries to pass the ham license, which 
would put the ticket around $20 for the first 
license. One of the last things we need now is a 
further discouragement for new licensees. 

May I propose a compromise? I would be 
willing to go along with even the $9 fee if the 
I CC would waive the fee on the first license 



issued to each amateur. I his would permit the 
youngsters to start out in amateur radio without 
being heavily penalized and then they would 
make up for the first free ride later on at renewal 
time or when they stepped up to a higher license. 
Presumably they would be in a better financial 
condition after five years than they would at 
first. 

If you have any thoughts on the matter you 
had better send them in to the 1 CC immediately. 
Though the date for comments on 18802 is now 
past. I am reliably informed that they will accept 
comments and put them with the file until the 
Commission makes its decision. Head your letter 
as being comments on Docket I KN02 and give all 
of your recommendations as well as your reasons 
for them. The additional 14 copies will help, it 
you have a copier handy* Even without, your 
letter may count. Send it to the FCC. Washington 
DC 20554. 

Do We Need Representation? 

Our ignoring of the problems of the ghettos 
resulted in an escalation of problems, not in their 
going away. Our ignoring of the growing prob- 
lems in the schools has had a similar result. I 
wonder if we are going to continue trying to 
ignore the problems besetting amateur radio? 

The FCC is about to more than double the 
license fee for us, Is on the verge of passing new 
rules for I M repeaters which could virtually slop 
the growth of this phase of our hobby and 
prevent amateur satellite development, and has 
just slugged us with the most extensive revamping 
of our bands in the historv of amateur radio. 
When are we going to stand up and say that 
things have gone far enough? 

The blacks decided to do something about 
their problems. . .and have had success. The 
students have started making themselves heard 
. . .with success. You. the amateur who is being 
done in, have yet to speak out and make yourself 
heard. Mow lone are vou soine to take it? Things 
don't have to go this way and you know it. As 
long as you continue to play the game with the 
same marked cards you are going to come out the 
loser. 

We need representation in Washington and we 
need it right now and we need it badly. We need 
someone who can protect the interests and rights 
of radio amateurs. . .someone who can talk 
turkey with senators and congressmen. - .who can 
talk with the ICC staff and find out whv we are 
getting dumped on and what can be done to stop 
it. We need someone who can talk with the 
military and get them to help us in our battles. 
They need us and should be reminded of this 
now- and then. We do not have this now. . .we 
need it 

DX Piteups 

An article by G3BID proposed that piteups 
"attract" and are self-inflating. Obviously he has 
something there, DXers Inning across the band 
listen carefully for pileups as a method of finding 
rare DX. Often they will leap into the pile 







MAY 1970 



11 



Incentive Licensing 
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without even knowing who they are calling. Tins 
comes out when they make the contact and have 
to ask in embarrassment for the call of the DX 
station they are working, 

Pilcups are caused by poor operating on the 
part of the DX operator. It is disappointing that 
so few DX operators avoid the time-consuming 
and frustrating pileup process. The system for 
getting the most contacts tn the least time, using 
only one frequency and virtually eliminating 
pileups, is simple, but when was the last time you 
heard anyone using it? 

Control of the situation is in the hands of the 
DX operator. Those wishing to contact him will 
follow his instructions as best they can in order 
to get that cherished contact. The op must be 
absolutely inflexible. He must set down the rules 
for getting through to him and then stick to them 
without exception, If he once breaks his own 
rules, then he has failed all of those who have 
been obeying them and they will have every 
reason to be resentful and even spiteful. 

The DX operator should set down his rules 
and repeat them every fcw f minutes for the 
newcomers. Rule number one is that all calls 
must be on the frequency of the DX operator. 
Rule two is that all calls must be just once, one 
five-second phonetic spelling of the call of the 
calling station and no wasting time by giving the 
call of the DX station. Rule three is that calls will 
come in the order specified by the DX operator, 
with no exceptions whatever. It might even bind 
the cheese better to announce that anyone calling 
out of order will be placed on a lid list and will 
be contacted after all others calling are worked. 

The problem for the DX op is to get the call 
letters through the interference. If the caUs are 
spread thin enough this is no problem. Let*s say 
that the band is open to the LL S, and you are the 
DX op starting a series of contacts. It usually 
starts slowly with one sharp operator noticing 
your signal and calling you. When you finish a 
short contact with him, two or three are calling. 
You work them faster and by that time there are 
tail-endcrs, breakers, and every type of ogre 
known to the rare DX op. Now is the time to 
swing into contest style operating. Announce 
your rules. Then stand by for a specific call area. 
If the one call results in nothing but a mess, ask 
for WAls. This will psychologically prevent Wis 
and Kls from calling you. If you ask for Wis, 
you will get all three prefixes. One WA1 should 
stand out enough to get some of the call. The fast 
breaks permit you to get this done very quickly. 
Work Kls next, then Wis. Finish up by asking 
for any other Is such as hams from other areas 
operating w /l w ; then you might ask for any DX 
calls with a 1 in them. Next start in on the 2s. 
You can check the 2s en masse first, then split 
them into WB2s, WA2s, K2s, and finally W2s. 
Don't forget to ask for DX 2s too - they will 
probably be there. If you forget them you will 
start hearing them breaking in and botching 
things up for you. 



12 



73 MAGAZINE 



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This system is the fastest one for DXirni vet 
devised. It also is great in that everyone listening 
to the frequency knows just what is going on and 
you will find thai the dozens or hundreds waiting 
to get through to you will help you enforce your 
rules. 1 1 only takes one single frequency so you 
are not hashing lip 100 kH2 as some incon- 
siderate DXers do. Also, you are making it easy 
inr the op who does* not have a SpUt-frequencj 
system with the callers spread out up and down 
the band, jamming dozens of contacts for others. 
Being fast, the calling stations get worked much 
quicker and few ever have to wait more than 10 
or 15 minutes for a contact. The fast activity on 
the frequency is as much a red flag for the DXers 
as a pileup. so you never run out of callers while 
the hand is open. 

The next time you hear some poor soul 
struggling with split frequency or tail enders. win 
not take the time to tell him how to operate. 
You would do the same for a lid in the U, S.. 
wouldn't you? 

The l)X op should remember to pass along 
the QSL information every few minutes arid to 
give his call frequently, phonetically. If things 
slow down a bit, it doesn't hurl to add a feu 
comments about the country you are visiting for 
the assembled multitudes. 

One other benefit of this super-fast system is 
that even the low-power stations will be able to 
gel through since you get right down to complete 
quiet at the end of working each call area. The op 



will find himself working even mobiles and 
transistor rigs, making it more fun for all con* 
cerned, 

European ops can be handled in exactly the 
same way* Split them up into countries and then, 
if required, prefixes. With any kind of opening 
die DLs and n\Is will have to be cut very thin to 
be sorted out. 

The split-frequency rubbish was perpetuated 
all too long because one well known DXer used 
it. It now appears that he used it because it 
permitted him to avoid contact with some ops 
rather than because il was fast. Let's burv this 
wasteful relic of the past. 

The Post Office Mess 

Isn't it more than strange that in 1970 we are 
sending letters just about the same as they were 
sent in colonial times? In this electronic age it is 
nonsense for us to have to write on a piece of 
paper and then send thai piece of paper to 
someone else for them lo get the mess-ige. 

Sure, there are some things that go well on 
paper. . .legal items such as wills, mortgages, etc., 
need some permanence, but most of our com- 
munications are read and then thrown out. Or, if 
they are kept, they take up a lot of filing space. 

At 73. we get Mime 200 subscriptions a day 
by mail. Two hundred envelopes, two hundred 
letters and two hundred checks. Add to this 
another fifty or so letters to the editor and other 
items. Over 80% of the mail in our country is 

( continued on page 111) 






MAY 1970 



13 




Ironic as it ma\ seem, I think the biggest 
stumbling block to the advancement of ama- 
teur radio is a luck of communication between 
the people who make the rules and the people 
who follow them. Consider that infamous anti- 
repeater docket, the product of a small group of 
nervous and suspicious individuals within the 
FCC. 

There are restrictions posed by Deckel L8803 
that can he explained with no rationalization 
other than the simple fact that the FCC is 
worried that amateurs will misuse spectrum. 
thereby creating more headaches for the Com- 
mission by virtue of a possible rash of intra- 
fraternity complaints of interference and the like, 
I suspect Docket 18803 is geared first to forestall 
any such misuse and second to keep the ham 
radio operation within the realm of the Commis- 
sion's archaic understanding. 

The plain truth is that the FCC has precious 
little underslandum of ham radio. I his fact casts 
no aspersions of ineptness on the good people in 
Washington, for they certainly mean well But 
consider the breadth of their jurisdiction: the 
billion-dollar broadcasting market, the interstate 
use of phone lines, the pathetically misused 
citizens 1 band, the pay-TV snake barrel, the 
crowded commercial, industrial, and govern- 
mental spectra. Is it unv wonder the handful of 
men in Washington have no real feel for what's 
doing with the comparatively trouble-free minor- 
ity group of ham radio? 

Paradoxical, yes, but fact: Those well 
meaning fellows in Washington are painfully 
ignorant as to the capabilities and limitations of 
radio as we know it. Attesting to this is the FCC's 
answer to Wayne Green's recent request for an 
extension to the deadline for filing comments 
about the license Tee increase, Wayne's reasoning 
was that more time was needed to disseminate 
the information. The ham journals needed time 
to publicize and editorialize; ham groups needed 
time to plan meetings mid have discussions before 
filing comments* Reasonable? To you and lo me, 
yes - but not to the I C( . The FCC told Wayne 
that amateurs in particular needed time the least, 
since hams all have communications capability. 

Obviously, the FCC has the idea that if one 
ham makes an on-the-air announcement, all 
others will immediatelv net the word. (And I 

■ 

guess most of us thought that way before we 
became hams.) The unfortunate thing is. how- 
ever, that the I Ci'\ official reason was less than 
no reason at all, and served only to illustrate the 
communications breakdown between the rule- 
passers and the rule-followers. 



1 must admit, albeit reluctantly, that the 
communications gap is not strictly limited lo 
failings on the part of the Washington bunch, I 
myself was guilty of misinterpreting when, in a 
rush to make deadline for the last issue of 73.1 
published opinions on a docket I hadn't yet seen. 
I lused my comments on a verbal description of 
Docket 18803, which resulted in mv erroneous 
assumption that remote operation would be 
illegal (because of the crossband restrictions). 
Everett llenrv called me from FCC headquarters 
shortly after the maga/ine came out to set me 
straight. 

Vm confident the FCC doesn't trust us. The 
people in Washington are wary of saying yes to 
anything because they're afraid of unleashing 
another holocaust like CB. Asa result, the ICC 
undoubtedly pores over e\er> petition about 
repeaters with exasperating caution. 

But are we any better? f traveled several 
hundred miles a few weeks ago to attend one of 
the many special meetings that are taking place 
across the count r> because of Docket 18803. The 
purpose of the meeting was to examine the FCC 
proposal, determine what action to take, and 
make a decision as to how best to act collec- 
tively or individually. We spent more than three 
hours discussing such simple trivia as how the 
proposed rules were worded! More than one of 
those amateurs attending the meeting was con- 
vinced that the ICC was trying to nail us with 
subtle wordings. And the result was that we spent 
our time trying to interpret sentences whose 
intent was pretty plain at a glance, We got 
nowhere and proved nothing except the fact that 
we don T l trust the I CC. either. 

Now, more than ever, I wish I were a sharp 
attorney. Vd like to present our case intelligently 
before the FCC. then listen to comments in 
opposition. I think Fd point out that ham radio 
needs policing the least of any radio service. Yes, 
I know the ICC has probably received more 
complaints about repeaters than any other ham 
mode -but repeaters have never been legally 
recognized, so they have alwaj s been a subject of 
controversy But the real case for repeaters is the 
case for public interest, convenience, and neces- 
sity. More than any other aspect of our hobby, 
repeaters fill this requirement. Rare is the re- 
peater that has no public service ties. And more 
and more common is the repeater that is relied 
upon b> local civil defense and other emerge nc) 
organizations. 

1 would appeal lo the FCC to put 1 8803 in 
abeyance, and adopt Docket 1542 as an interim 
measure, in the same manner as the government 
of our Canadian neighbors has done. Let us prove 
our worth. Let us have the opportunity to do 
what we're licensed for - to serve our purpose lo 
the best interest of the public. There is no clear 
and immediate need for a tight set of restrictions. 
Even the FCC can see where the proposed 
restrictions are detrimental to public interest. 
What we really need is relaxed restraints so we 
can develop and grow, and prove even more 
valuable to the communities in which our re- 
peaters are situated, K6MVH ■ 















14 



73 MAGAZINE 




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I find ii incomprehensible, listening to the 
remarks of some hams, otherwise quite placid 
and mild mannered, when the subject gets around 
to fellows who wear their hair longer than most 
of us do. There would appear to be a hidden 
spring of sadism which wells up to the surface 
and overflows, and it requires very little stimulus 
to start this unreasoning thing a-going. But after 
all* lefs face it: long hair does not a ^hippie" 

make. 

A certain party I've always liked was heard to 
expound on this subject. "If I'd had a pair of 
scissors in my pocket, 
Pd have given some of 
those guys a haircut!' 1 
Now, of course, this is 
silly, been use a chap's 
haircut is no index to 
his political per- 
suasion or any tiling 
else. If you doubt 
that, just turn your 
memory backward 
and visualize the late 
Senator Everett 
MeKinley Dirksen. If 
ever there was a man 
with a more disrepu- 
table looking mop of 
kapok on his noggin, 
I'd like to know who. 
Yet no one ever 
foul ted old Ev. Least- 
wise, not about his 
leonine tonsure. Mat- 
ter of fact, that un- 
ruly hairdo was one of his most notable charac- 
teristics, second only to the mellifluous foghorn, 
that voice with which he spoke the best English 
extant. . -unique and famous the world over. 

On the other hand, in the first days of the 
Russian Revolution every Bolshevik in good 
standing shaved his pate clean. I presume that 
this was proof positive that he had undergone the 
delousing process regarded as de rigueur at that 
time in that unhappy land. So far as I know (and 
I couldn't care less) they still need the delousing! 

You cannot tell anything about someone's 
political or social persuasions on the strength of 
physical appearance. Unfortunately there are 
some reds who wear the cloth. And there are 
Cosa Nostra torpedoes who lctok like bankers and 
members of the Union League, And I remember a 
highly successful female film star who made the 
list of the ten best dressed women several times. 
Actually, she needed a hath so badly she stank to 
high heaven! 

Now that I reflect upon it, 1 don't think my 
friend would really attack anyone with a pair of 
scissors. As I visualize his all- too-evident head full 
of pink, shiny skin, drawn as tightly as a 
snaredrum head, I think it was probably just a 
case of pure green-eyed envy. 

That's all. 




Nobody asked me, but . . . 
. # . Why do some would-be "control stations*' try 
to set up net-style operations during ordinary, 
roundtable ragehews? They grandiloquently 
announce, "John, you give it to Joe. Joe will turn 
it over to George; George, you pass it to Pete; 
Pete will give it to Charlie, and Charlie will turn it 
back over to me/* If they're so all- fired anxious 
to act like traffic cops, why don't they join the 
police department? 

. . , Why is it that when the band is almost devoid 
of activity, and you're having a nice quiet chat 

f with an old friend, 
some thoughtless 
creep starts counting, 
"One, two, three, 
four, four, three, two, 
one. Testing, testing, 
testing/* right on 
your frequency, or 
even worse* 500 Hz 
away? Why is it? 
. . . How come some 
guy in contact with a 
rare DX station will 
start to describe his 
shack, the color uf his 
wallpaper, the ages of 
all his six kids, his 
wife's operation, his 
bursitis, why he 
switched from vox 
back to push-to-talk, 
and who was the King 
of Albania when he 
got his first license? 
And how come this always happens when there 
are 479 other guys trying to get a contact, 
especially when the signals are starting to fade 
into the rising noise level How come? 

New Math 

As a public service, and to uphold the dignity 
of us fuddy-duddies of the older, more benighted 
generation, I'd like to say a few words about the 
so-called "new math 1 ' that some of the kids are 
bringing home from school these days, it is 
disconcerting, doubtless, to hear seven- and 
eight-year-old tykes uttering mystifying and for- 
mid able terms such as "sets, subsets, commuta- 
tive and associative properties'* and the like. In 
our day, and I blush to admit it, plain old plus 
and minus were obstacles enough, and I distinctly 
recall that it took me weeks to learn my 
multiplication tables. 

The essentia! thing about the new math is that 
it seeks to he precise, and also avoids the use of 
misleading inaccuracies of the past. I remember 
being told, "You can*t subtract 9 from 7, M for 
example, and then making the discovery that I 
could indeed subtract, obtaining minus 2 as the 
answer. Nowadays kids are taught the essential 
structure of the subject. , .the why, rather than 
the how, . .through plane geometry* algebra, 
number lines, binary arithmetic and sets. They 



16 



73 MAGAZINE 





n 



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HENRY RADIO 
PRESENTS 





PACKAGES YET! 



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Hy-Gain TH2MK3 $240.00 

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Complete with one of the following 
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Hy-Gain TH6DXX $760.00 

The Magna Mast is ideal for stacked 
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TED HENRY (W6U0U) BOB HENRY (W0ARA) WALT HENRY (W6ZN) 



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Butler, Missouri 64730 816/679-3127 

'"World's Largest Distributor of Amateur Radio Equipment" 














arc also being introduced to analytic geometry, 
probability, and Boolean algebra. . all of which 
were previously restricted to college level courses. 

The new teaching, called the discovery 
method, is worlds removed from the old teaching 
by rote. By means of a sort of Socratic question- 
posing technique, children are steered into inves- 
tigating for themselves the world of numbers. 
The premise is that what is absorbing and 
intellectually intriguing is fun, and consequently 
learned more quickly and more lastingly. 

Many parents, unwilling to relinquish the old 
methods which they learned in school, are 
finding it difficult to catch on to the new math. 
Because one of the most important roles of 
father and mother continues, in spjte of changes 
in attitudes, to be the preservation of a sense of 
respect for ciders in their offspring, this is getting 
to be a problem. The kids cannot seem to 
generate much respect for elders who cannot 
seem to grasp intellectual concepts which they 
themselves find logical and understandable. 

There is an interesting little book, published 
by the American Book Company, entitled "What 
About This Modern Mathematics Business?" {A 
Handbook for Parents.) This book, simply writ- 
ten, explains in clear terms the material which is 
covered in these new school programs. I recom- 
mend it to you earnestly if you are puzzled about 
this subject. 

After all, what are you going to tell your 
youngster when he asks, "Gee, Dad, will you help 
me make a Mobius Strip to take to class 
tomorrow," or, **Say, Mom, what's the difference 
between the decimal, duodecimal, and binary 
numeration systems?" 

Atrophy 

I write a semiweekly column for a suburban 
newspaper in the area where I live. In casting 
about for subject matter (I am not restricted in 
any way), it struck me that I might discuss ham 
radio. In my column I pointed out that this 
would be a splendid opportunity for channeling 
the energies of youngsters in a meaningful and 
constructive way, I pointed out that there were 
no acid-heads or glue sniffers. . .no hubcap 
thieves or child molesters. . .and probably very 
few radicals or revolutionaries in ham radio. 

I also pointed out that apart from the 
enjoyable aspects of the hobby and the oppor- 
tunities to perform public services in many ways, 
participation could also unlock the doors to very 
rewarding careers in electronics, I closed the 
column by inviting inquiries, and stated that I 
would refer all such to regional and local amateur 
radio clubs, so that the matter of license and 
equipment could be dealt with. 

As a result of the appearance of this column 1 
received several dozen replies. There appeared to 
be an enthusiastic body of area residents, most 
interested in becoming involved. This included 
many adult persons in addition to young people. 
In three instances the queries involved entire 
families, both parents and children. This large 



response was extremely gratifying, and I was sure 
thai in a short period there would be some new 
amateurs in this area, a most desirable develop- 
ment from every standpoint. 

I am chagrined to have to report that I was 
not able to find too much club activity here. The 
nearest club to me has been hors de combat for 
the past two or three years. There do not appear 
to be any truly active radio clubs anywhere in the 
immediate vicinity, outside of some which are 
specifically slanted toward individual ham activi- 
ties such as DX or VHP. Consequently, 1 have 
had to combine my own personal efforts with 
those of some ham friends, in order to get these 
folks oriented, trained, licensed, and equipped. I 
have not been able to find a single active radio 
club functioning here. This is a sorry state of 
affairs, particularly since there was a great deal of 
club activity hereabouts in prior years. 

The high schools, a natural place for the 
formation and growth of such clubs, are almost 
totally devoid of any interest in the matter. One 
of the main reasons for this is the failure of 
school boards to provide any funds for this type 
of activity, and, since the budgets d*< not call for 
any expenditures in this area, there are few 
teacher-hams who could be expected to stand the 
cost personally, much as they would like to do 
so. It is unfortunate thai while there are al\va> 
enough funds to purchase footballs, twirling 
batons and hockey pucks, somehow the schools 
do not seem able to buy the most inexpensive 
pieces of used radio gear, so that radio clubs can 
be activated where they might do some good. 

I should like to urge all the readers of Leaky 
Lines who live in communities where a similar 
situation exists to instigate programs of their 
own, in order to awaken interest in amateur radio 
among area residents. Where the school boards 
appear to be unenthusiastic in their response to 
the idea, public demand for such programs may 
possibly inspire a change in direction. I am 
confident that there is not a science department 
in a single school which does not include a 
teacher who would be willing to assume the 
trusteeship or leadership of a ham radio club. 
Offer your services and make yourself available 
to such people so that your neighborhood school 
may become a spawning ground for future hams. 
If we address our energies to such projects there 
is no doubt that many clubs can be activated. 

We all owe a debt to this hobby we love so 
well. I suggest that one of the most concrete 
ways in which we can repay it is to see that our 
enthusiasm is passed along to the youth. If we 
can institute and maintain a viable, ongoing pro- 
cess of ham recruitment, we will not only be 
supplying our hobby with a vital flow of new 
blood, but we will be contributing toward our 
nation's health by helping to provide construc- 
tive, positive and meaningful channels of activity 
for our youngsters. What could be more impor- 
tant tli an that? 

...K2AGZ" 









18 



73 MAGAZINE 



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SPECIAL REPORT 



73 Comments on FCC's 

Proposed Repeater Rules 



any of us by now have had the 
opportunity to study Docket 18803 care- 
fully. For the benefit of those who have 
not, I think it is safe to say that this 
proposal is the most important since incen- 
tive licensing, and more devastating to the 
future of VHF amateur radio than any rule 
change bid in our history. For repeaters, 
the proposal changes are stiflingly restric- 
tive and growth-stopping. For remote oper- 
ation, the proposed rules are disastrous. 
With these rules, there can be no satellite 
translators, no mobile remote control oper- 
ation, no city-to-city links, no cross- 
country systems. Docket 18803 spells 
instant death for remote operation as we 
know it, and imposes complex repeater 
hardships — and this is no exaggeration. 
Every radio amateur - VHF'er or low-band 
operator, repeater owner or not, remote 
devotee or CW enthusiast - owes it to ham 
radio to do everything in his power to stop 
this proposal from getting passed, To do 
this, here is what you must do: Read the 
FCC-proposed rule changes reprinted here, 
then write your comments. Send the origi- 



nal and 14 copies of your comments to the 
FCC in Washington, D.C. before May 15. 
This is absolutely essential. You must send 
alt 15 copies before May 15. 

The FCC Proposal (Docket 18803 
Appendix) is printed in italics below. The 
comments of the 73 editorial staff are 
incorporated in close-spaced bold-face 
type. Your comments may or may not 
coincide with those of 73. At any rate, you 
have the chance to see what we think of 
each item in the proposed rule changes. 
Make your own comments independently 
if you like; or, if you feel as we do, tear 
our comments out, sign it, then make 14 
copies and send the whole works to 
Washington. 

If you're involved in a repeater that has 
public service ties, get affidavits and sup- 
porting documentation from your local 
government authorities. Remember — they, 
too, have the right to make comments, 
since their operations are directly affected 
by the proposed changes, and they do 
represent the public, whose interest is 
supposed to be served by amateur radio* 




20 



73 MAGAZINE 




/. In § 97.3, a new paragraph (i) is added to read as follows: 

% 97,3 Definitions 

fi) Amateur Repeater Station. An amateur station at a specified fixed location used to 
automatically retransmit signals of other amateur stations. 

2. Section 97.41 is amended by adding a new paragraph (bj as set forth below, and 
redesignating former paragraphs (b) and (c) as fe) and fdj. 

§ 97 A I Application for station license. 

fh) Each application for a remotely controlled station shall be filed on FCC Form 610 
or FCC Form 61 OB, as appropriate, and must include a supplementary statement giving 
the address of the remote control point and indicating whether control will be by wire or 
radio, If remote control is by radio, complete information must be furnished showing 
how the transmitter is controlled and what means will be used to prevent unauthorized 
operation of the transmitter. Data on control frequencies, the function of all relays, 
timing devices used for control, directional transmitting and receiving antennas in the 
control system, and other pertinent details must be included. 

3. A new § 97.42 is added to read as follows: 

§ 97,42 Station location. 

Every station must have a fixed transmitter location. Only one fixed transmitter 
location, which will be designated on the station license, will be authorized unless the 
station is authorized to be operated by remote control. 

4. Present § 97 A3 is deleted and new § 97 A 3 is added to read as follows: 



Amateur Remote Stations 

§ 97 A3 Remote Control of an Amateur Station. 

(a) k emote control of an amateur station other than an Amateur Repeater Station 
from a point or points specified on the station license may be authorized provided: 

(1) The remote transmitter is so installed and protected that it is inaccessible to 
unauthorized persons. 

(2) That in addition to complying with § 97,85, a photocopy of the Amateur Station 
license is posted in a conspicuous place at the remote transmitter location. 



MAY 1970 



21 



{3} The emissions of the transmitter are continuously monitored at the control point. 

{4} The radiation from the transmitter can be immediately suspended from the control 
point when there is any deviation from the terms of the station license or the 
requirements of this part. 

(5) The station is so designed and installed that the transmitter can be activated only 
from the authorized fixed control point. 



Such exclusive activation restricts the operation of a remotely controlled station 
to the detriment of the public interest, convenience, and necessity. No mobiles, for 
example, would be allowed to access the remote station, which is at present perhaps 
the most valuable type of installation for public service applications, would be 
restricted in such a manner that it would be virtually worthless for all uses except 
the relaying of signals to and from the control operator's base. 

One life— at least— was saved already because of an amateur's ability to access his 
remote transmitter and phone patch from hfe car. On a stretch of freeway near Los 
Angeles, a motorcycle officer had a heart attack and spilled. Motorists stopped but 
no one could help. Don Milbury W6YAN didn't even stop. He accessed his remote 
autopatch as he passed the scene, and called an ambulance and the local authorities. 
The policeman might have died without the prompt medical aid that came as a 
direct result of Don's call. Amateur radio paid its way that day, and no one could 
say that Don Mtlbury's brand of radio is not in the best public interest. If this part 
of the FCC proposal gets through, operation of a remote station from a car will not 
be legal. 

On another occasion, two amateurs in Pomona, California saw a hit-and-run 
accident, and telephoned the police from their car using the remote control 
facilities of K6MVH. The two hams followed the suspect car while they kept up a 
running conversation with the police dispatcher, who radioed update location data 
to patrol vehicles in the vicinity. Within minutes, the suspect vehicle was 
intercepted. The local police were impressed with the hams' communications 
capability. It is doubtful that this local government considers amateur radio to be a 
TVI-generating nuisance, as so many others do. 

As a suggested alternative rule change for the above-proposed item, how about 
this: 

(5) The station is so designed and installed that master control can always be 

effected from the fixed control point, and access from the fixed control 

point shall at all times be capable of overriding all other input signals. 

This suggested alternative proposal leaves the door open to operate and control a 

remote station from a hand-held, portable, or mobile unit, as long as an authorized 

monitor has the capability of exercising master control from the fixed station. 



(6) That if remote control is by radio, the control link is direct, without intermediate 
relay* 

Here, again, is a rule portion that does not appear to be in the public interest. 
Master control of the remote transmitter, of course, should be "direct" without 
intermediary relay. But there should be no rule against indirect control as long as 
the direct control is maintained from the fixed site, Many remotely controlled 
stations are situated in such a manner that "direct* 1 control from a low-power 
station is impossible because of distances, terrain, etc* To circumvent the problems, 
an intermediary station is set up so that user stations can transmit signals that can 
be relayed to the remote transmitter. Back-to-back repeater stations are examples 
of indirect control of a remote facility; they allow installation of phone patches 
even when there are no phone facilities at the basic remote location. They allow 
range extension when the users live out of the area where most of the Fftf action is 
taking place. In addition, they offer the only means whereby users of one remotely 



22 



73 MAGAZINE 




NEW Heathkit SB 102 . 





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The New Heathkit SB- 102 . . . proud descendant of 
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We improved the already excellent frequency sta- 
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The "102" receiver is even hotter than the famed 
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copy longer when the band is on the way out. 
The new "102" . , , the famous flexibility & per- 
formance of the "101" plus important new features. 
Put the hot new SB- 102 in your shack now. From 
the Hams At Heath, of course, 

SB-102, 23 lbs + , . , ♦ $380.00* 

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impedance headphone. Power output: 2 watts with less than 10% 
distortion. Spurious response: Image and IF rejection better than 
50 dB, Internal spurious signals below equivalent antenna input of 
1 microvolt. TRANSMITTER SECTION: DC power input; SSB: 
ISO watts P.E.rV continuous voice, CW: 170 watts — SO 4 ,," duty cycle, 
RF power output: 100 watts on 80 through 15 mefers; 80 watts on 
10 meters (50 ohm nonreactive load). Output impedance: 50 ohms 
to 75 ohms wilh less than 2:1 SWR r Oscillator feodthrough or 
mixer products: 55 dfl below rated output. Harmonic radiation: 
45 dB below rated output, Transrn it-receive operation; SSB: 
Pufth-to-talic or VOX. CW: Provided by operating VOX from a keyed 
tone, using grid-block keying. CW side-tone: Internally switched to 
speaker in CW mode. Appro* 1000 Hz tone. Microphone input 
impedance: High impedance. Carrier suppression: 50 dB dawn 
from 5»ngfe-tone output, Unwanted sideband suppression: 55 dB 
down from single-tone output at 1000 Hz reference. Third order 
distortion: 30 dB down from two-ione output. Noise level: At least 
40 dB below single-tone carrier. RF compression {TALC): 10 dB 
or greater al A ma final grid current. GENERAL: Frequency cov- 
erage; 3,5 to 4.0; 7.0 to 7.3; 14.0 to 14.5; 21.0 to 21.5; 28.0 to 2B.5; 
28,5 to 29.0 ; 29,0 to 29.5 > 29,5 to 30,0 {megahertz). Frequency sta- 
bility: Less than 100 Hz per hour after 10 minutes worm-up from 
normal ambient conditions. Less than 100 Hz for ±10^ line voltage 
variations. Modes of operation; Selectable upper or lower side- 
band (suppressed carrier) and CW. Visual dial accuracy — '*re- 
setfability": Within 200 Hz on oil bands. Electrical dial accuracy: 
Within 400 Hz after calibration at nearest 100 kHz point. Dial mech- 
anism backlash: Less than 50 Hz. Calibration: 100 kHz crystal. 
Audio frequency response: 350 to 2450 Hz ±3 dB, Phone patch 
impedance: 3 ohm receiver output to phone patch; high impedance 
phone patch input to transmitter. Power requirements: 700 to 800 
volts ai 250 ma; 300 volts at 150 ma; — 115 volts ai 10 ma; 12 volts Ot 
476 amps. Cabinet dimensions: \A%* W x 6H" H x 13?^' D. 



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controlled facility may access and command another such station, situated perhaps 
many miles from the first site. 

In California, New England, and Nevada, for example, experiments have been 
performed and systems are currently being built that allows repeater groups to 
access the repeater facilities of other repeater groups by mutual consent. The UHF 
control facilities for the WB6SLR remote station in California could be used to 
interrogate the control system for the K7TDQ remote station in Las Vegas. If 
K7TDQ is willing to allow his repeater to be an input/output terminal, he could 
electrically command his system to respond to the control signals of the VVB6SLR 
machine in California, The result is a Los Angeles to Las Vegas repeater system 
interconnected by a controllable 450 MHz link. 

Similar cooperative efforts have taken place along the eastern seaboard when 
Gordon Pugh K2GHR exercised control of several repeaters in New England and 
Canada from his own remotely controlled station. 

Repeater expansion along the lines of metropolitan interconnections — currently 
being planned between northern and southern cities of California, between Tulsa 
and Wichita, San Diego and Phoenix, Los Angeles and Las Vegas, and perhaps SO 
other places in the country — cannot take place without allowing "indirect" control 
of a remotely situated station, 

(7) That if remote control is by radio, the control transmitters operate on frequencies 
within a band above 220 Mcfs. 

(8) That if remote control is by radio, a timer is provided to automatically limit 
transmission to a period of three minutes in the event of failure of the radio control link, 
capture of the control receiver by an undesired signal, or other technical malfunction. 



Amateur Repeater Stations 

i 

(b)Remote control of an Amateur Repeater Station may he authorized provided: 

(1) The installation and operation of the station complies with paragraph fa) of this 
section. 

(2) The station is provided with an automatic timer to limit a single uninterrupted 
transmission to a period of not more than three minutes. This circuit may be so designed 
that it will automatically reset but will not permit use of the transmitter until receipt of a 
properly coded signal. 

The last sentence in this segment should be replaced with: "This circuit may be 
so designed that it will be automatically reset but will not permit reactivation of the 
repeater until receipt of a properly coded signal/' The wording differences between 
this and that proposed by the FCC are quite subtle, but the reason will be clear 
when the comments to (4) below are understood. 

(3} The station is so designed and installed that overriding control of the station is 
maintained from an authorized remote control point. 

(4) The station is so designed and installed that the transmitter can be used only upon 
receipt of a coded tone signal after the transmitter has been activated from the control 
point. 

There are two major types of coded repeater control in very common use, both 
of which offer the protection from inadvertent interference that is the purpose of 
such control methods. The first type of control is "tone burst entry/' where a 
coded tone is required of each repeater user at every transmission in order for his 
signals to be repeated. The second type, single-tone activation, is commonly known 



24 



73 MAGAZINE 




I 

as "whistle-on," and allows the repeater to be activated for uncoded carrier 
operation when the user whistles on the input frequency. In the whistle-on system, 
the repeater continues to operate on a carrier-operated basis as long as the repeater 
is in constant use* When a short time goes by with no input signals, the repeater 
automatically deactivates, and must be "whistled on" before it can be again 
activated. The rule as proposed by the FCC does not provide for this very 
functional form of subcontrol, and places an undue burden on all repeater 
operators to the effect that ALL users must equip their units with tone generators. 
The intent of the rule can be satisfied without the necessity for all operators 
installing tone-burst equipment if the rule in question were to be modified as 
follows: 

The station is so designed and installed that the repeater can be used only 
upon receipt of a coded tone signal after the transmitter has been activated 
from the control point; or, in the case of a whistle-on tone system, the 
repeater can be energized for carier operation provided that a means is 
incorporated for automatically deactivating the repeater within 3 minutes 
after the last signal is received. Reactivation after this period can be achieved 
with a tone from the repeater input frequency only if the repeater has been 
properly activated from the control point. 

(5) The station is so designed and installed that the transmitter will be silenced within 
five seconds after cessation of the output of its associated receiver. 

J, In § 97.61, the introductory text of paragraph fa) is amended, and a new paragraph 
fc) is added to read as follows; 

§ 9 7.61 Authorized frequencies and types of emissions. 

(a) Following are the frequency bands and associated emissions available to amateur 
stations, other than Amateur Repeater Stations, subject to the limitations stated in 
paragraph fh) of this section and § 97.65. Frequency bands available to Amateur 
Repeater Stations are shown in paragraph fc) of this section, 

(c) Amateur Repeater Stations must receive and transmit in the same frequency band. 
Simultaneous transmission in two or more frequency hands is not permitted. The 
following frequency bands and the emissions authorized in those bands in paragraph fa) 
of this section are available for Amateur Repeater Stations: 

52.50-52.70 53.00- 53.20 
Input (Receiving) Mc/s Output {Transmitting) Mc/s 

52.50- 52 JO 53.00- 53.20 

146,30 - 146,60 146.90 - 147.20 

223 JO- 22 3 JO 224.10 - 22430 

447. 70 - 448.90 449.10 - 449.30 



Any amateur frequency a bore 1215 Mc/s 

The intent of this part of the proposal is to lessen the congestion caused by 
multiple transmissions of repeaters and to minimize the interference caused by 
crossband operation, where monitoring of the output before transmission is 
difficult and impracticable. The outlawing of 6-to-2-meter systems seems reason- 
able, because both bands are active, often crowded, and are in general use by 
amateurs using a variety of modes. 

But who could deny the attributes of a crossband system between 2 meters and 
220 MHz, or between 6 or 2 meters and any of the UHF bands, or between one 
UHF band and another? Is this not the next logical step in amateur repeaters? And 
is this not the only practicable method by which amateur orbiting satellite 
translators and repeaters can evolve? 



MAY 1970 



25 



In the interest of furthering the development and natural growth of amateur 
radio, there should be no restrictions between erossbanding on these higher 
frequencies, where the bulk of the activity is already provided by the individuals 
who inhabit the spectrum for the sole purpose of exploring and exploiting the 
capabilities of advanced communication forms. 

The frequency restrictions of the above subband allocations are also unduly 
restrictive. Not only would these allocations render a large number of existing 
repeaters illegal, but they pose problems to the repeater users that are only 
questionably solvable within the existing state of the art (such as the narrow spread 
in the 450 MHz region). 

There are obvious advantages to restricting repeaters to specific portions of the 
spectrum, and virtually every VHF operator knows this; for this reason, amateur 2 
meter FM operators — including repeater owners and users — have unanimously 
agreed to populate only frequencies above 146,04 MHz, and then only those 
frequencies that are spaced at multiples of 30 kHz from one another. In highly 
congested areas where there is an abundance of FM activity, operators have made 
unwritten agreements to reduce deviation levels to ±5 kH2 at least on alternate 
channels, and in many cases they have reduced deviation to narrowband standards 
on all FM fchannels, Since channelized operation is universally accepted in the 
United States (and Canada), there would seem little need to establish discrete band 
portions for transmitting and receiving. Rather, it would seem in the best public 
interest as well as in the interest of amateur radio, to allow FM repeaters to be 
established on existing channels, depending on the activity, operating conditions, 
and individual requirements of the areas where the repeaters are to be used. In some 
cases, the repeater input should be higher in frequency than the output; in others, 
the reverse would be more locally suitable, And in some instances, as in separated 
sites, the transmitting and receiving portions of the repeater could best be placed on 
the same frequency (as has been done successfully in several installations). 

6. Section 9 7.67 is revised to read as follows: 

§ 97.67 Maximum authorized transmitter power. 

(a) Transmitter power is the dc power input to the final r.f amplifier* If the final 
amplifier is of the r.f grounded-grid of r>f grounded-base type, the transmitter power 
also shall include the d.e. power input to the stage which immediately precedes the final 
r.f amplifier. 

fb) Except as limited by §97.61 (b) transmitter power shall not exceed: 

fl) 600 watts for transmitters used at Amateur Repeater Stations. 

Since the difference between 600W and the 900W maximum legal limit of 
remotely operated transmitters represents but a barely noticeable amount (less than 
2 dB), little is to be gained by this restriction. An amateur repeater should be 
allowed to operate with the same power restrictions faced by other amateur stations. 

(2) Two kilowatts for single sideband radiotelephone transmitters and other amplitude 
modulated radiotelephone transmitters using reduced, suppressed, or controller carrier 
when measured during maximum peaks of modulation; 

(3) One kilowatt for all transmitters other than those covered by subparagraphs fl) 
and f2) of this paragraph. 

ft) Equipment capable of operation with transmitter power in excess of 90% of any 
applicable power limitation shall have installed a means for accurately measuring 
transmitter power, 

7. Section 97. 79 is revised to read as follows: 
§97*79 Operator Requirements. 



26 



73 MAGAZINE 




(a) An amateur station may be operated only by a person holding a valid amateur 
operator license issued by the Federal Communications Commission and only in the 
manner and to the extent provided by the class of license held by the operator or the 
station licensee, including the trustee of a club station, whichever is the lesser. 

(b) The licensed operator required by paragraph (a) of this section must be on duty at 
the transmitter location or at an authorized control point 

(c) An amateur station licensed as a military recreational station may be operated only 
in the manner and to the extent provided by the class of amateur license held by the 
person operating the station. 

(d) When an amateur station is used for telephony or radioprinter transmissions, any 
person may transmit by voice or teleprinter, provided a licensed amateur operator is 
present at the operating position, continuously monitoring the transmissions and 
maintaining supervisory control of the station, including turning the carrier on and off for 
each transmission and signing the station off after communication with each station has 
been completed. 

8. In § 97*87 1 new paragraphs (ej through (h) are added to read as follows: 
§ 97.87 Station identification. 

fe) In lieu of the requirements of paragraph (a) of this section, an Amateur Repeater 
Station may be automatically identified by radio telegraphy at intervals not to exceed 

three minutes by keying on audio tone superimposed on the voice transmissions. The 
code speed shall not exceed 20 words per minute, and the modulation level shall be 
sufficient to be readable through the voice transmissions. 

This should be modified to permit automatic identification by telegraphy or 
recorded voice. 

ff) A station licensed to an individual may be identified by its assigned call only when 
operated by or under the immediate supervision of the station licensee. If the station 
licensee, who is the owner of the equipment, is not present, the operator must identify 
his transmissions by using his own call sign with the appropriate portable indicator. 

Should also state: An Amateur Repeater Station will be identified only by its 
designated call regardless of which authorized control licensee is monitoring from 
an authorized control point. 

fg) A club station may be identified by its assigned call only when operated under the 
supervision of the trustee or an authorized club member. 

(h) A military recreation station may be identified by its assigned call only when 
operated by a member of the Armed Forces of the United States who holds a valid 
amateur operator license. 

9. Section 97.89 is amended to read as follows: 
§ 97.89 Points of communication. 

(a) Amateur stations may communicate with: 

(1) Other amateur stations. 

(2) In emergencies or for test purposes, and on a temporary basis, with stations in 
other services licensed by the Commission and with United States government stations. 






MAY 1970 



27 



(3) Any station, other than an amateur station, which has been authorized to 
communicate with amateur stations. 

(b) Notwithstanding the provisions of paragraph (a) of this section, an Amateur 
Repeater Station shall not repeat the transmissions of another Amateur Repeater Station. 

It is absolutely essential to the growth and technological development of UHF 
and VHF amateur radio that such restrictions are not imposed. Dual repeaters are 
invaluable for some applications, such as public service functions outside the area 
normally served by a repeater. 

As an example, the Wichita repeater is heavily depended on by the local 
government to provide early warning for maximum evacuation effectiveness. Like 
any other repeater group, the Wichita repeater users have mobile units and 
hand-held transceivers, which are used in conjunction with the repeater to provide 
an effective communications system. But what happens when the alert is out of the 
area of immediate coverage of the repeater? With the FCC restriction of no multiple 
repeaters, civil defense usefulness suffers, because the mobiles and hand-held units 
of the group are worthless without the repeater — the heart of the communications 
system. 

On the other hand, if multiple repeaters were not illegal, the repeater crew could 
take a portable UHF repeater to the scene to act as an intermediary system, 
extending the range of all low-power units so that the immovable repeater in 
Wichita could still be used as if the disaster point were actually in Wichita. The 
intermediary repeater could be no more than a temporary setup designed to operate 
from emergency power or from the power source of an automobile. This is how 
such a system works: 

Hand-held units transmit on 146,34 MHz and receive on 146*94 MHz, 
frequencies compatible with the permanent repeater. The intermediary repeater 
receives on 146.34 and retransmits on the UHF control frequency for the 
permanent repeater. The control receiver at the permanent site relays the UHF 
signal to 146*94 and to another frequency in the UHF range. The intermediary 
repeater accepts the UHF signal and retransmits to 146.94, thereby allowing all 
low-power user stations to communicate through the permanent repeater by virtue 
of the dual relay. 

Interlinking of repeaters is a vital step in VHF progress, and is one of the most 
attractive features we have to offer municipalities when we try to show them our 
communications potential. Using a multiple repeater system, it is now within the 
state of the art to set up a system of links so that user stations in one city could 
actually select, via a special access link, repeater interconnections in other cities. 
With the advent of communications satellites, UHF dial-a-city could become a very 
common practice —and it could be designed so as to be completely compatible 
with existing systems on a noninterference basis. 

The proposed rule stated in (b) above should be reworded as follows: 

Notwithstanding the provisions of paragraph (a) of this section, an 
Amateur Repeater Station shall not repeat the transmissions of another 
Amateur Repeater Station except by mutual consent of the responsible 
principals of all repeaters to be affected by such a multiple relay. 

10. Section 97 A 03 is revised to read as follows: 

§ 97 J 03 Station tog, 

(a) Each licensee of a station other than an Amateur Repeater Station shall keep a log 
of station operation which shall include the following: 

(1) Except when operating mobile, the date and time of each transmission or the 
beginning and end of a series of transmissions. 

(2) When operating mobile, the date and time station operation commences and ends. 
(3} Call sign of the station called. 



28 



73 MAGAZINE 




(4) If the transmissions are made through a repeater station, the call sign of the 
repeater. 

(5) The signature of each licensed operator who operates the transmitter from the 
transmitter location or control point and the date and time of such operation. 

(6) The name of any person other than the operator who directly or by recording 
transmits by voice or transmits by radio teleprinter. 

(7) The input power to the transmitter. 

(8) The frequency band or subband used. 

(9) The type of emission used. 

(10) The station location. 

{11} If record messages are handled, a copy of each message sent and received shall be 
entered in the station log or retained on file for at least one year. 

(b) The licensee of an Amateur Repeater Station shall keep a log of operation which 
shall include the following: 

(1) The date and time station operation commences and ends. 

To avoid misunderstanding, this should state *\ , .the date and time repeater is 
placed in service and is accessible by user stations who comply with access 
requirements/' 

(2) The entries specified in subparagraphs (5), (7), (8), (9), and (10) of paragraph (a) 
of this section. 

(3) A record of all installation, service, or maintenance work performed which may 
affect the proper operation of the station. 

(4} The entry required by subparagraph (3) of this paragraph shall be made, signed, 
and dated by the licensed amateur operator who supervised or performed the work. 

(c) The entries required by subparagraphs (5), (7) $ (8) t (9) f and (10) of paragraph (a) 
of this section need only be entered once until there is a change in the required 
entry. 

11. In § 97.193, the introductory text of paragraph (a) is amended, and a new paragraph 
(e) is added to read as follows: 

§ 97 J 93 Freq uencies available. 

(a) Except as provided in paragraph (e) of this section, the following frequencies and 
frequency bands and associated emissions are available on a non-exclusive basis to the 
indicated classes of stations or units of such stations in the Radio Amateur Civil 
Emergency Service. 

There should be no subband restrictions above 51 MHz. 

(e) A repeater in the Radio Amateur Civil Emergency Service may operate on any 

frequency and associated emission above 50 Mc/s listed in paragraph fa) of this section. 

There should be no subband restrictions above 51 MHz. 



MAY 1970 



29 



WHAT 



BECOME 



If you look all the way back to the 
beginning of ham radio and then trace 
its development up to the present day, you 
will see some very interesting trends. For 
purely academic reasons it is interesting to 
see where we have been. It's like studying 
history. In addition, by noting the various 
trends that have occurred, we may be able 
to predict where we are going. I think that 
one of the most interesting trends to look 
at is the use of the various modes like CW, 
AM, SSB, and RTTY, Statistics are hard to 
come by here to verify these trends, but I 
believe we can still make some general and 
useful observations without them. One 
particularly interesting phase of this is the 
history of CW, Let's take a look at the 
mode trends over the years to see if we can 
predict what will happen to CW. 

When ham radio first began, all we had 
was CW, first by spark then by normal 
means as .we know it today. As the 
technology of radio and electronics devel- 
oped, we soon had radiotelephone by 
amplitude modulation. The convenience of 
voice communications made AM popular 
among hams even though it was more 
expensive to use, would cover less distance, 
and was more succeptible to noise. FM 
came along soon after: it too gained some 
followers, These gains in radiotelephone 
work were made at the expense of CW. 
Those operators that used to work CW, 
were now working phone or some of both. 



Louis E. Frenzel, Jr. W5TOM/3 
11287 Columbia Pike 
Silver Spring MD 20901 



So as the years passed and radiotelephone 
became more widely used, CW activity 
decreased. 

I believe it is safe to say that ever since 
ham radio began, there has been a con- 
tinued decrease in the use of CW. The 
major reason for this is simply the con- 
tinued and increased use of radiotelephone 
techniques as they are introduced or 
become more perfected. The introduction 
and rapid increase in the use of SSB no 
doubt has taken its toll of CW operators as 
well (AM operators too for that matter). 
The equipment manufacturers have helped 
by making many reasonably priced radio- 
telephone transceivers, some of which have 
absolutely no provision for CW operation. 
That's progress, brother. 

There are also other factors that have no 
doubt influenced the trend of decreased 
CW activity. For example, in the early 
fifties the FCC did away with the "Class 
A" license phone privileges and opened the 
75 and 20 meter phone bands to all 
amateurs. This seemed to have an almost 
immediate effect of increasing phone oper- 
ation and correspondingly decreasing CW 
activity. The increased use of the VHF and 
UHF bands has probably caused a similar 
but rather indirect decrease in CW work. 
As more hams go to these higher frequen- 
cies, CW activity tends to decrease. Who 
uses CW on the VHF and UHF bands 
anyway? 



30 



73 MAGAZINE 




By just listening to the various CW 
bands you certainly wouldn't think that 
CW activity has decreased much. But the 
somewhat overcrowded conditions are the 
result of an increase in the total ham 
population. CW activity as a whole has 
increased because the total number of 
hams has increased , but percentagewise it 
has decreased. Today CW is probably in the 
30 to 40% usage bracket while phone is in 
the 40 to 50% range. The total doesn't add 
up to 100% because some hams use both 
modes, of course, This overlap plus some 
of the special modes like TV, RTTY, pulse, 
etc. make up the difference. 

Having noted the trend of decreased CW 
activity, what can we say about the future? 
Will CW continue to decrease in popularity 
or what? What do you think? I'll give you 
my prediction here. 

I sincerely feel that the incentive 
licensing plan now in effect will produce a 
slight increase in CW activity. The exclusive 
band segments are a big incentive for a ham 
to bone up on his code to get his extra 
class license. As most everyone knows, one 
of the best ways to get your code speed up 
is to get back on the air and work some 
CW. In fact, this is by far the easiest way. 
Regular and intense practice with code 
records or Wl AW will get you there faster, 
but it will be more difficult* 

The extension of the Novice license 
term to two years may also cause a slight 
increase. With more Novices on for longer 
periods of time, CW activity just may 
increase. After all, Novices work CW exclu- 
sively. 

The slight upward trend will probably 
only be temporary or will show up perhaps 
just as a less rapid decrease in CW activity. 
I think that it is safe to predict a continued 
decrease over the long term. We'll just have 
to wait and see. 

The Case for CW 

Frankly I hate to see CW on the down 
swing. All things considered it's probably 
the best mode of communications available 
to us. It is cheaper and simpler to use than 
any other mode. Using it, you can cover 
more distance with less power under noisy 
and crowded conditions than any other 
mode. And it's the only way to handle 
normal and emergency traffic. These 
obvious advantages are continually over- 



looked because it's so much easier to just 
talk. It requires less concentration and skill 
to operate phone. I don't think most hams 
give CW a chance. Most consider it little 
more than a nuisance, something they have 
to learn in order to pass the license exam. 
Once they have to learn it well enough to 
pass the exam, it is virtually forgotten until 
renewal time. If hams would consider CW in 
a different light, we might see more activ- 
ity. Don't look at CW as a necessity or a 
drudge. Look at it as a rare, if not unique, 
skill that most other people do not have, 
and be proud of this skill. 

Another point is simply that CW 
becomes easier and more fun the more you 
use it. It's like anything else unfamiliar, 
The more we use it, the more comfortable 
we become with it and the more we will 
tend to uSe it. Get in the habit of using CW 
and I bet that in a short time you will like 
it. Your code speed will go up, you will be 
more adept at tuning and copying, and 
soon it will all become automatic, like 
driving a car. You won't consciously think 
about doing it. 

I have found that two items really help 
to increase the pleasure of operating CW. 
One is a good electronic keyer and the 
second is a good selective receiver. With an 
electronic keyer you can send nearly per- 
fect code. This is particularly appealing to 
a CW man. A good sounding "fist" really 
stands out. It's a definite mark of accom- 
plishment, In addition, the keyer itself is 
intriguing. It takes a little skill and prac- 
tice, of course, to master one, but yet it 
isn't so difficult as to cause frustration. 
Most hams, being incurable gadgeteers, find 
electronic keyers fun to play with and a 
challenge to use. If you are not now on 
CW, buy or build yourself an electronic 
keyer. You'll go nuts until you can get on 
the air and use it. 

Electronic keyers make a good cheap 
and easy home project if you are inclined 
to do things yourself. There has been at 
least a jillion articles on them over the past 
ten years or so in the ham magazines, so 
you shouldn't have any trouble locating a 
suitable design to build from. On the other 
hand, if you don't like do-it-yourself pro- 
jects, there are numerous good commercial 
units available. Get an electronic keyer and 
enjoy some CW. 



MAY 1970 



31 



The other item that helps to make CW 
more enjoyable is good receiver selectivity. 
The key to good CW reception is to have a 
receiver capable of separating stations oper- 
ating near the same frequency. Nothing is 
more annoying than to lose a good contact 
to QRM even if his signal strength is very 
high. An adjacent station can easily wipe 
him out. However, if your receiver is 
selective enough, you can probably 
separate the two interfering stations and 
carry on a decent QSO, 

If your station receiver isn't selective 
enough, you might consider an outboard 
Q multiplier or tunable audio filter. These 
are easy to add and do a good job in 
providing the needed selectivity; Neither 
requires extensive receiver modifications. If 
you plan to operate a lot of CW, it will pay 
to invest in the most selective receiver you 
can find to begin with. 
Whaf s in Store for CW? 

Changes over the years have helped to 
cause a decline in CW interest. As AM, FM f 
and SSB became popular and more per- 
fected, CW probably suffered some from 
loss of interest, However, this is not to say 
that all of the technological changes going 
on didn't have some effect on the business 
of CW itself. It most certainly did. The 
electronic keyer is certainly one develop- 
ment that we can point to. Not only do we 
have small, exotic, integrated circuit 
keyers, but also pushbutton, typewriter- 
like keyers are available. These offer 
improved convenience in that no CW 
sending skill is required- Just push the 
button and out comes the perfectly formed 
dots and dashes for that letter. 

The opposite of a pushbutton keyer is a 
device that receives the code and auto- 
matically converts it into a visual display 
easily read by an operator. Such devices do 
exist, but they are complex and expensive. 
Their big advantage, like their pushbutton 
keyer counterpart, is that absolutely no 
CW skill is required. If you know your 
ABCs, you've got it made, Numerous code 
receivers like this have been developed for 
commercial and military use. They are so 
expensive that they are virtually imprac- 
tical for ham use. Nevertheless, I guess if 
they were available, some hams would buy 
them. Perhaps with modern integrated cir- 
cuits, an inexpensive unit could be built. 



Even though pushbutton keyers and 
automatic code receivers are entirely 
possible, I'm not too sure that they are the 
answer to the CW question. Since no skill is 
required, there is really no challenge 
involved. Of course, this is the way it is 
with phone operation, so maybe such 
devices could really go over big. If these 
units could be made available to everyone 
at a reasonable price, the FCC could do 
away with the code test and we could all 
still operate CW without even knowing it. 
Transmitters would have built-in keyboards 
while the receivers would contain CRT, 
Nixie tube or some other form of alpha- 
numeric readout displays, 

In the not-too-distant future, perhaps 
we will see such things in common use. It 
will be a sort of RTTY, only using elec- 
tronic means entirely and the standard 
international code instead of mechanical 
devices and the Baudot code. It will be sort 
of like using a computer. We can put the 
data in and interpret the output even 
though we don % t know how the computer 
actually works internally. (Is that the 
definition of an "appliance operator? 11 ) 

Somehow I just can't see much of this 
in ham radio. This takes away the pride 
and the skill of sending and receiving. And 
I feel that this is still important. 

In conclusion, I say we will continue to 
see a gradual decline in CW activity. The 
incentive licensing thing may help to hold 
it up for a while but in the long run we will 
see less of it. I get the impression that 
people feel that it is a thing of the past, an 
inconvenient, cumbersome, and obsolete 
method of communicating. Perhaps so, but 
there is still a feeling of tradition and pride 
that will help it to hang on for years to 
come. You'll never experience this feeling 
yourself unless you work CW for a while. 
Give it a try. Get yourself a keyer and a 
selective receiver and have a go at it. You 
might like it. If you really want to be a 
pioneer, try CW on 6 or 2 meters. There is 
less QRM up there, more room to move 
around in, and CW seems to be ideal for 
these bands. Since propagation essentially 
restricts the range you can cover, it makes 
good sense to use CW to help you reach as 
far as you can. CW will go a lot farther 
than phone up at these frequencies. See 
you there. - . . W5TOM ■ 



32 



73 MAGAZINE 



• •• 



for get me ! 



m TRANSISTOR TftANSCTl 



i ft* SAtT 



%J • 



$<mwcH 



&f> &A1H 



CH.smcr 



..: 






FOFM-2 



it 






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■ - 

i mill 






\f. JJNQUiE CQMMUNEtfiiiGItt EQUt^MthfTS CGnp 



know my big brother, IC-2F, is a bit stronger and maybe a little better lookin', but don't 
forget I've got a few things goin' too! I hear real good at0.4uV. I'm completely portable 
with a battery pack and my own antenna, besides working at home with an AC power 
supply or in your car ... I can go anyplace with you. I have some RF amplifier friends 
that will help me out if needed. I'm still the best 5 watt input unit on the market. 
Besides, I play for a $100 less than my brother. 

See the FDFM-2 two meter FM 
transceiver at your dealer now. 



Varitronics Incorporated 

Arizona Interstate Industrial Center 
2321 East University Drive • Phoenix, Arizona 85034 



Ed Goldsby W3JKL/DL4UC 
Ramstein Air Base 
Germany 



FM-AM Transmitter- Receiver Aligner 



Many articles and ideas have been 
published in recent months which 
have been slanted toward the VHF FM'er, 
Most of them have been directed to the 
attention of the receiver. Little mention 
has been made of the transmitter. 

I have been using receiver peaking and 
aligning generators for several years now, 
and since I am in the FM communications 
business as a profession, I have often 
wished that I had a small transistorized 
instrument that would take care of trans- 
mitter frequency and loading adjustments 
along with the receiver peaking. 

The gadget I have conceived cannot be 
construed to be a precision test instru- 
ment; however, it does fulfill most of the 
requirements of the average VHF FM 
operator* 



M9029 



^3-1* 




\zfiH 



5 30 



F/S METE* 



047 



SPKR 




1 



■ ST **6. 3/a in Oia 
CENr£wTAPP£0 
OUTPUT TAP, l TuftN UP 
FROM COLO END 




KJK|-— 



AMPL 



33011 



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W 



Basically, it starts off with the usual 
peaking generator, (a crystal oscillator and 
multiplier) followed by a diode mixer/ 
detector and an audio amplifier with 
enough power to drive a small speaker. 

The peaking generator, while gener- 
ating a small signal for receiver alignment, 
also provides enough signal to the diode 
mixer to heterodyne with a signal from 



the transmitter which, when amplified in 
the audio section, may be used to align 
the transmitter to the receiver fre- 
quency - or any other preset crystal fre- 
quency. Simply tune the transmitter oscil- 
lator for zero beat in the speaker. 

The circuitry also provides for connec- 
tion of a relative field strength meter. 

In addition to its VHF applications, it 
works equally well in the HF bands. In 
my unit, I included a crystal for our local 
40 meter MARS net frequency. 

I chose to use PNP transistors because 
I had a 5 pound box of them. In the 
oscillator, I used a 2N384 and it took off 
strongly as soon as I applied battery vol- 
tage to it. 

I tried several unmarked transistors in 
the multiplier and some of them worked 
pretty well, but the one I wound up using 
was a Motorola M9029. Upon checking it 
out, I found that it is commonly used as 
an rf amp li Tier in some VHF receivers. I 
could find no equivalent 2N number for 
it. 

For the multiplier coil, I used 5 turns 
of 1 6 AWG centertapped for the collector 
and an output tap one turn up from the 
cold end. 

The diode mixer/detector was arrived 
at by "cut and try" also, I still don't 
know what the number is because there 
were no markings on it — not even the 
usual color bands. However, it works well 
at VHF frequencies and delivers enough 
output current to drive my field strength 
meter to the pin (500 juA) at some dis- 
tance from the transmitter. 

For the audio section, I used one of 
those little Japanese 1W units I got from 
Allied Radio for $4.95, but I could have 
used the audio portion of one of those 
little pocket receivers. 

. . . W3JKL/DL4UC ■ 



34 



MAY 1970 






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mm 

Many articles, manuals and even full- 
length books are devoted to anten- 
nas In general and as specifically applicable 
to the amateur radio service. Unfortu- 
nately, one of the most effective simple 
antennas for both local ground-wave and 
long-haul DX communications on the 
higher frequency bands is almost invariably 
conspicious by its absence. Consequently, 
few amateurs are familiar with the char- 
acteristics, design, or construction of the 
5/8-wavelength vertical antenna. 

It will be immediately apparent to most 
amateurs that the 5/8-wavelength vertical 
antenna will provide an omnidirectional 
radiation pattern and a vertically polarized 
signal. And the antenna itself will be 2Vi 
times as tall as the more familiar ^wave- 
length vertical or groundplane. What will 
not be so obvious, to the uninitiated, is the 
even lower angle of vertical radiation, the 
gain obtainable and an additional improve- 
ment in reception due to increased capture 
area over the conventional ^-wavelength 
antenna. 

These characteristics have made the 
5/8-wavelength antenna very popular in the 
land mobile services and in amateur 2 
meter FM operations where omnidirec- 
tional vertically polarized ground-wave 
communications with low-power mobile 
stations are desired on a full-time basis. 

Vertical antennas, almost invariably of 
the Vi-wavelength variety, have been widely 
employed in the amateur radio service for 
DX communications where their low angle 
of radiation {assuming an adequate ground 



35 



73 MAGAZINE 




system) has proved very effective. Since 
the polarization of radio signals is generally 
rotated significantly in the process of 
reflection, cross-polarization losses are 
seldom a consideration in sky-wave com- 
munications. 

Unfortunately, the additional advan- 
tages of the 5/8-wavelength antenna have 
seldom been employed for normal amateur 
communications. True, a 150 ft vertical for 
75 meters or 80 ft for 40 meters is beyond 
the facilities of most amateurs. However, a 
30 ft antenna for 1 5 meters is well within 
amateur capability, and 50 ft (20 meters) is 
within the realm of reason. 

Theory of Operation 

As a short grounded vertical antenna is 
increased in length, the radiation lobe 
narrows, increases in intensity, and the 
angle of maximum radiation lowers toward 
the horizon. As the length exceeds Yi 
wavelength, a secondary lobe of radiation 
at high vertical angles develops; but the 
low-angle radiation continues to increase 
until a height of 5/8 wavelength is reached 
(Fig, 1). With no equalizing factor, as the 



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40 



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Fig, J, Low-angle radiation increases as antenna 
length increases up to 5/8 wavelength. 



length is increased beyond 5/8 wavelength, 
the high-angle radiation increases and the 
low-angle radiation decreases. 

Since the 5/8-wavelength antenna is 
nonresonant T it presents a highly reactive 
load impedance unsuitable for direct feed- 
ing. At least three basic methods are 



available to transform this impedance to a 
50Q nonreactive feedpoint. 

Probably the simplest method is use of a 
small series inductance as shown schemati- 
cally in Fig. 2. The inductance can be 




Fig. 2. 5/8-wavelength vertical base-loaded to 3/4 
wavelength with series inductance. 



considered as base loading the antenna to 
3/4 wavelength {with no change in the 
radiation pattern). This is a resonant length 
which will present a feedpoint resistance of 
approximately 50£2, a very close match to 
RG-8/U or RG-58/U coaxial cable. Adjust- 
ments to the loading coil should provide an 
swr of less than 1.2:1. In the groundplane 
configuration, some additional improve- 
ment in swr can be obtained by dropping 
the radials. Approximately 30° below the 
horizontal will be about optimum with a 
resulting swr of less than 1.1:1. This 
configuration has the advantage in simpli- 
city and ease of construction and tuning. It 
will also be relatively broadbanded when 
fabricated of materials of adequate 
strength. 

The second feed method utilizes a 
parallel-resonant circuit tuned to the oper- 
ational frequency with the feedpoint 
tapped at a low impedance point on the 
coil, as shown in Fig. 3. This arrangement 
may be considered as providing high- 
impedance feed to the base of the radiating 
element and a direct ground connection to 
minimize ignition noise and provide a 



MAY 1970 



37 



H 





Fig. 3, S/8-waveiength vertical using paraHel-tuned 
-circuit feed, 



Fig. 4. S/8-waveJength grounded vertical with gam- 
ma match feed. 



degree of lightning protection. Coaxial 
feedpoint tap adjustments in conjunction 
with minor tuning changes can provide 
nearly a 1:1 sw* at the operating fre- 
quency. 

The tap point and tuning adjustment 
interact slightly and initial adjustments are 
slightly more time-consuming. However, 
the coil— capacitor combination can he 
grid-dipped to the approximate frequency 
on the bench so that only minor touch-up 
is required. 

This configuration has the additional 
advantages of providing a very low swr 
without decoupling-radial droop or when 
mounted on a mobile installation. It will 
not normally be quite as broadbanded as 
the first. 

A third method of feeding is through 
the familiar gamma match, as shown in 
Fig, 4, Here the radiator itself is grounded 
and the feedline is tapped onto the radiator 
through a series capacitance. This arrange- 
ment also provides a direct ground con- 
nection for minimization of ignition noise 
and a reasonable degree of lightning pro- 
lection. Feedpoint tap variations combined 
with series capacitor adjustments can pro- 
vide nearly a 1.0: 1 swr at the operating fre- 
quency. 

This configuration is particularly adap- 
table to feeding existing grounded towers as 



ground system of heavy radials will be 
required. 

Design 

The 5/8-wavelength vertical radiator 
should be reasonably close to a full 5/8 
wavelength at the desired frequency but 
should preferably be no longer. Conse- 
quently, the decoupling radials should be a 
5/8 wavelength at the high end of the hand 
of opera lion. Conversely, the decoupling 
radials should be a minimum of Va wave- 
length at the low end of the operating 
band. The following formulas are based on 
reasonable velocity factors for materials 
probably available in amateur construction 
and should prove adequate for preliminary 

design purposes. 

7020 



Radiator length, in. = 



Radiator length, ft = 



fin MHz 

585 

f in MHz 



or 



Decoupling radial length, in. = 



Decoupling radial length, ft = 



2880 



f in MHz 
240 



or 



f in M Hz 

Using these dimensions, the coupling 
circuit can then be selected to resonate or 
provide minimum swr at the desired oper- 
ating frequency. Though theoretically any 
coil or coil— capacitor combination which 
can be resonated at the desired frequency 
would work, it is important that good 
tank-circuit design principles and full 



38 



73 MAGAZINE 




weather protection be considered to 
minimize circuit losses and provide for 
maximum energy transfer. In general, this 
implies that all coils be space-wound with 
large wire or tubing and that length-to- 
diameter ratios be less than 4:1 (and 
preferably 2:1 I. Capacitors should be high 
quality, ceramic insulated or wide air- 
spaced variables for ease of circuit adjust- 
ment and reasonable power handling capa- 
bility . 

The coaxial feed tap point will vary 
with different constructional methods and 
materials and the optimum point must be 
determined experimentally for each instal- 
lation. It will invariably be quite close to 
the ground end of the coil, varying from 
approximately 1 turn on 2 meters to 
possibly 3 or 4 turns on 20 meters. 

Construction 

While this is not intended as a "hard- 
ware" style construction article, a few 
approaches possibly worthy of further con- 
sideration have been accumulated. 

Conventional TV masting or aluminum 
tubing is readily available, rugged and 
inexpensive, although insulation and instal- 
lation are more difficult than with some 
other materials. 

Of course, the surplus whip antenna 
segments and their matching insulators are 
relatively inexpensive, free standing to 
heights approaching 20 feet; they are rela- 
tively light in weight and are available from 
numerous sources. 

Insulated (or even grounded) antenna 
towers should make effective radiators for 
the lower frequency bands, providing an 
adequate ground radial system is incor- 
porated. 

On 2 meters or even 6, a fiber-glass 
fishing pole covered with shield braid from 
RG-8/U and RG-58/U makes an ideal radia- 
tor. Of course, 1/8 in. welding rod works 
adequately on 2 meters or higher bands 
also. 

Although this antenna will probably not 
compete with a good beam or quad at 
optimum elevations above ground, it is a 
very effective antenna, readily and eco- 
nomically fabricated with minimum facili- 
ties, 

, .. WA0NGV" 




Feature This^\ 




SIGNAL/ONE'S CX7 GIVES YOU 

Instant Band Change 
Without Tune Up. 

Remember when . . . you missed 
that really rare one . . . because he 
showed up on 10 when you had a 
hot string going on 20 and couldn't 
take the time to retune? . . . Or had 
to move clear across a band to meet 
a traffic net and were late getting 
there? . . . Well, if you don't, 
Signal/One engineers do and did 
something about it! By putting 
state-of-the-art technology to work 
in a: 

■ BROAD BAND DRIVER m m m 

totally solid state and linear from 
1.8 to 30 MHZ; it provides free- 
dom from driver peaking adjust- 
ments. 

■ BAND PASS P,A. output filters, 

pre tuned for every ham band 
from 160 through 10 meters. 

These remarkable features actually 
allow band change from one band 
to any other band in the middle of 
a sentence without the time con- 
suming tasks of reresonating . . . 
that's state-of-the-art flexibility. 



"It Speaks for ttself" 




A Division of ECI (An NCR Subsidiary) 

2200 Anvil Street No. 
St. Petersburg, Fla, 33710 



MAY 1970 



39 



^™ 







1 Meters 



m 




The FM mode may have been shelved 
with the spark-gap had it not been for 
an FCC action concerning the commercial 
FM mobile service. Years back when the 
commercials were growing by leaps and 
bounds, it became obvious that the available 
channels were overcrowded. Since spectrum 
space was at a premium, narrower FM 
bandwidths were adopted in order to create 
more channels. Now the wideband equip- 
ment had to be converted over to narrow- 
band at a cost which often exceeded the 
equipment value, or it was junked in favor of 
new equipment. Many progressive outfits 
went the latter route. This increased the 
"surplus" trickle of FM gear to a torrent. 
And amateurs, the ingenious scavengers that 
they are, scooped the units up at bargain 
prices. Realizing the potential use of this 
equipment, many hams converted the units 
for 6 or 2 meters or to the 432 MHz region 
(FM'ers call it "450"). Clubs and individuals 
got together and fired the units up on the 
unused higher band edges and thus a major 
change was born. These units were fixed 
frequency and the new concept of "channel- 
ized" communication was brought into ama- 
teur radio. Unlike the equipment used by 



the early pioneers, the fixed frequency was 
new to hams and proved to be an advantage. 

After a while across the country standard- 
ized channels were adopted by the various 
groups. As more gear appeared on the 
market, more amateurs got on FM. Still the 
growth was only moderate. It was spurred 
onward by word of mouth and by curious 
amateurs who found something besides 
images on the higher two megahertz of their 
"Gooneybirds," 

Hams, using FM for mobile work, fol- 
lowed the commercials' lead and set up 
repeaters to extend the range of communica- 
tions. At first these groups numbered be- 
tween 3 to 20 hams as a rough average. Then 
FM started to receive the attention it de- 
served in the various amateur publications. 
This brings us to the topic of "The Intelli- 
gent Use of 2 Meters FM," 

Ed Tilton (ARRL, QST official) once said 
that repeaters "are self-defeating." There can 
be a lot of truth in these words, but it 
doesn't have to be so. What would prompt a 
statement of this sort? Well, during the last 
few years FM has been growing in drastic 
proportions. In the last few years magazine 
articles on FM increased interest and many 



40 



73 MAGAZINE 




repeater groups found their systems filled to 
overflowing with new traffic. Many systems 
fell apart or moved to less populated chan- 
nels. So it seemed the blessing of channel- 
ized communication was actually a curse. 
This unforeseen problem seems to be more 
of an operator problem rather than a space 
problem in most cases. One fact is that an 




This Motorola trunk-mount rig is characteristic of 
the two-way units of the '50s. A built-in dyna- 
motor powers the transmitter, while the receiver is 
driven with a vibrator supply. The control head, 
shown with mike attached f connects to the unit 
with a long cable. 



amateur obtaining a surplus FM unit rarely 
equipped it for anything but the repeater 
input frequency on his transmitter and the 
local repeater output frequency on his 
receiver. 

Ideally, a ham using a repeater should be 
able to transmit on the repeater output 
frequency as well as the input, allowing 
"direct" operation without using the re- 
peater. The use of a repeater to ragchew 
with a lone ham across town is stupid. The 
use of a repeater located 20 miles outside of 
town to talk across town is equally stupid, 
and both instances are examples of a lack of 
courtesy to fellow system users. 

Few FNTers seem willing to upgrade the 
receiving portion of their unit. They feel 
that if they can hear the repeater that is all 
that there is to it, Period. Case closed. What 
nonsense! Most units at best are only pass- 
able for repeater use and almost useless for 



extended direct work. One interesting point 
which has not been made is the "capturing 
effect*' where a strong signal will take over a 
weak one on an FM receiver. The stronger 
will usually take over the limiters and the 
weaker is unheard. Let's use our imagination 
and explore this point further. Suppose we 
have four hams on an FM channel using 
identical equipment, Hams A and B live in 
Get own; and 10 miles away C and D live in 
Reaville. Between both towns is a repeater 
on a slight knoll. Ham A can talk to B, and C 
can talk to D with no interference to each 
other because of relative signal strengths. 
Suppose B and A decide to talk to each over 
the repeater, Certainly A and B can converse 
via the repeater, but C and D were blasted 
off channel by the needless use of the 
repeater! 

Please don't get me wrong, I have nothing 
against repeaters. A well thought out and 
maintained one is not only a joy to use, but 
a pleasure to listen to. A repeater requires 
careful attention for the channels used, and 
the technical problems would fill this maga- 
zine. In many areas the standard channels 
are so crowded that it would be impossible 
for a new repeater to go into operation 
without interference to itself or others. It 
takes only one lid to reduce a system to 
shambles. 

A ham just getting into the FM game 
finds a new and strange world when he*s first 




In the early '60s, transistor units made thek 
appearance. The two shown here are GE "Voice 
Commanders, " The unit out of its holster is getting 
a battery charge from a GE supply built into a 
control head housing. 






MAY 1970 



41 



*m 



introduced to a repeater. AH that is needed 
to be successful is common sense and some 
knowledge of the operating procedure used. 
For instance, you should never hear a CQ 
called. Common practice would be, 'This is 
K1ZJH mobile monitoring '94* direct" or 
"K1ZJH repeat via W1BNF monitoring 94." 
This is all that is needed— if any of the group 
is around you will "break" their squelch 
with your call; and if they feel like chatting, 
they'll let you know. Contacts through a 
repeater are kept short, especially during 
"busy" hours when everyone is on the road, 
say on the way to or from work. 




Some of the early portable units, such as this 
Motorola PZ5 f used "hybrid 1 * circuits, with tube- 
type transmitters and transistor receivers. The 
lower half of the unit shown is a ni-cad battery 
pack, and can he replaced with the ac supply 
shown at left. 



A QSO is thrown back and forth like 
VOX operation, to a lesser degree. Mono- 
logues are frowned upon. This allows 
a breaker to join or the party to bow out if 
he has arrived at his destination. Many 
( indeed, most) repeaters have dropout timers 
that will shut the system off if a continuous 
signal stays on the input for over a specified 
period (usually 3 minutes), Generally speak- 
ing, there is no time limit for the use of 
repealer. It is left up to the intelligent use of 
the user; the system is left in your hopefully 
responsible hands. 

One very irritating thing new system users 
seem to enjoy doing is keying the repeater 



on and listening to it "come back." (Some 
can sit back and do this for hours.) While 
most outgrow this habit before long, the 
repeater operators get *'up tight" when they 
hear someone playing games with their 
system. If you practice such tactics, you will 
be labeled as a trouble source, 

A prospective FIVTer will find, while 
browsing through the lists of available FM 
units in the ham magazines, a bewildering 
array of letter prefixed multidigited units 
listed with no other description present. The 
best way to find out what would best serve 
your needs and pocketbook would be to 
contact an FM'er who has had some experi- 
ence. While everyone has his own brand of 
preference, generally Motorola , GE, and 
RCA gear are best bets since (1) they are still 
in business, (2) technical data is easier to 
come by for these units, and (3) there will 
always be someone around town familiar 
with their circuitry. Also, there are sche- 
matic sourcebooks on the markets for GE 
and Motorola gear at present. 

Once you select and buy your unit, learn 
how it works and get familiar with working 
on it. The number of new hams who can fix 
the guts of the equipment in their car trunk 
is sadly deficient. This is one item which 
cannot be crated up and sent back to Heath! 

The first rig you will want to acquire will 

most likely be a mobile unit for the car. A 
good mobile starts at $75.00 and units 

converted to the ham band generally run 
$25.00 to $50.00 more. Try to do the 
conversion yourself with the aid of an 
experienced ham. That will help you learn 
about the unit. Generally, only a retuning is 
needed, and sometimes some of the coils 
may have to be padded to bring them into 
correct range. The mobile unit might well be 
considered as your major piece of gear. The 
quarter-wave whip mounted on the trunk lid 
or roof of the car is widely used. Higher gain 
coaxials or 5/8-wavelength verticals rate sec- 
ond and are moderately expensive. 

Various stunts can be used to improve the 
transmitter. Eliminating the dynamotor with 
a transistor supply and swapping 6146s for 
2E26s is a typical modification. Since the 
average mobile receiver has a sensitivity of 
0.7 jUV (at a quieting factor of 20 dB), your 
best investment is a preamp. A Nuvistor job 



42 



73 MAGAZINE 





EVER 





REPEATER 



If you haven't 

already received 

a copy of our NEW 

1970 Catalog of Precision 

Quartz Crystals & Electronics 
for the Communications Industry, 

SEND FOR YOUR COPY TODAY! 




Somewhere along the line, in vir- 
tually every ham repeater in the 
world, you'll find a couple of Sentry 

crystals. 

Repeater owners and FM "old- 
timers" don't take chances with 
frequency— they can't afford to. A 
lot of repeater users depend on a 
receiver to be on frequency, rock 
stable... in the dead of winter or the 
middle of July. The repeater crowd 
took a tip from the commercial 
"pros" a long time ago— and went 
the Sentry Route. 

That's one of the reasons you can 
depend on your local repeater to be 
there (precisely there) when you're 
ready to use it. FM'ers use the 
repeater output as a frequency stan- 
dard. And for accuracy, crystals by 
Sentry are THE standard, 

IF YOU WANT THE BEST, 
SPECIFY SENTRY CRYSTALS. 



'Ask the Hams and Pros 



Who Build Repeaters! 




SENTRY MANUFACTURING COMPANY 

Crystal Park, Chickasha, Oklahoma 73018 

PHONE: (405) 224-6780 

TWX -9 10-830-6425 



will bring a 0.7 jiV receiver down to 0.5 fiW 
or better in most cases. Reworking the front 
end will get you down to 0.3 juV or better 
with a little effort. 

If you do a lot of traveling, you may 
desire to work into ,the repeater systems in 
the areas you travel through. The hope for a 
network of repeaters all on a national input 
and output is unfortunately impractical. 
With the number of 2 meter stations cur- 
rently operating, there would always be 
someone from system A getting into system 
B and vice versa. Cooperating between 
groups has not always been in the ham spirit 
Paul Segal wrote about, either, The frequen- 
cies of 146.34 MHz in and 146.94 MHz out 
seem to be the most commonly used for 
repeaters (see Repeater Directory in this 
issue). On 6 meters, 52.525 MHz is consid- 
ered to be the main repeater output channel. 

W1BNF. the repeater which serves Cen- 
tra! Connecticut, recently added a 146.37 to 
"98" repeater system. The 146.37 MHz 
channel had to be created because there 
were no more available channels in the 
populous New England area! What this boils 
down to is that you may have to "multi- 
channel" your unit so that you can take 
advantage of all of the systems you will want 
to use or have access to. To do this, some 
hams stop their cars, go to the trunk, and 
manually change crystals as they get into 
different repeater areas. This is acceptable so 
long as you don*t have to do so often or on 
superhighways. Crystal switching can he 
done by diode networks, relays (reed relays 
are ideal), or remote oscillator decks. Com- 
mercial units having more than two crystal 
positions for the receiver or transmitter are 
rare and expensive. 

Most hams, after being on FM a while, 
eventually desire a base station for home 
use. Base stations which do get into the ham 
market command high prices; however, con- 
verting a mobile unit for base use is re la- 
tively easy since the power supply is the 
only major modification to be made in such 
instances. Motorola has provisions for separ- 
ating its series into three discrete sections: 
receiver, transmitter, and power supply. A 
receiver may be removed from a mobile unit 
and used as a base receiver. Several months 



later it may be used as a mobile unit by 
simply inserting it into the mobile case. 
These "strips" (as they are often called) are 




The large base stations usually have sufficient room 
to contain not only a complete repeater, but the 
control equipment and UHF gear as well This rack 
contains 2 and 6 meter FM equipment as well as 
power supplies and "Jink" equipment. 



available for quite reasonable sums, Since 
Motorola (and some others) generally uses 
the same series of crystal frequencies for 
their entire line of transmitters, it might be 
advisable to employ the same make unit in 
the base as the car. Receiver crystals don't 
always follow this rule because of different 
i-f configurations. 

In the past few years, a series of hand- 
held units (dubbed "bricks" because of their 
size and shape) have been hitting the market* 
These solid-state wonders are very popular 
among hams because they were made surplus 
in commercial service by the advent of even 
smaller units, containing integrated circuits. 
The bricks sell in the S 300.00 bracket and 
are made by Motorola. These units make 
ideal second rigs because of their portability 
and convenience. But without a repeater, 



44 



73 MAGAZINE 



VHP FM MONITOR RECEIVER 





Only 
$79.95 
Postpaid 
in the U.S.A. 






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IN U.S.A. 

The new VANGUARD FMR-150 is not just another frequency converter but a complete FM re- 
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Check the following features and see why it's the best. Collins I F filter for separating those closely 
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image frequencies* Dual Gate MOSFET RF stage for low noise. .2 uv. sensitivity, and minimum 
cross modulation* Automatic squelch for eliminating noise* Self-contained speaker* Operates on 
12v. D.C. negative ground* Heavy gauge anodized aluminum case 6" x 7" x 1-3/8"* Provision for 
4 crystal controlled channels at the push of a button* One channel of your choree supplied with 
receiver. Additional channels available just by plugging in another crystal at $4,95 ea. No need to 
buy another RF unit as in some other sets* Factory tuned to cover any 6MHz segment from 135 

to 175 MHz. 

HOW TO ORDER: The VANGUARD FMR-150 is available only direct from our factory. Include 

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want to cover and the exact push button frequencies to be included. 



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their utility would be sharply reduced. At 
any rate, the brick can be a lot of fun if 
some of your friends jump on the band- 
wagon with you. 

High-power solid state mobile gear made 
by all the big manufacturers is now hitting 
the ham market in small quantities (but 
usually at prohibitive prices). Watch for 
price breaks in the next few years on these 
items. (I was going to get one, but it was 
worth more than the can) 

As a final note, 1 should mention the 
equipment which has come out in the past 
year for ham use. These units are generally 
all solid state and sport multifrequency, 
small size, battery operation, and several 
other features. The price is around $300.00 
for the latest one I have seen. The Galaxy 
people have marketed a unit for under 
5200,00 which, besides all of its other 
extras, offers variable speech clipping! 

This article should familiarize the uniniti- 
ated with at least the basic rudiments of FM 
operation. I hope I have helped the beginner 
avoid some of the common pitfalls which he 
might have otherwise stumbled into. 

... K1ZJH" 




XfMf 



m HAVE A ZfrTHEg NOVEL 
SWA iNOfCAWM HE/IE, OM„* 



MAY 1970 



45 



M 



B- 



NeilJohnson W20LU 
74 Pine Tree Lane 
Tappan NY 10983 





A lot of ham operators toss around the 
decibels quite knowingly, but behind 
this facade of glib gab s there remains the 
simple fact that some of the best talkers 
really don't know what's going on. You 
can hear it on the air every day, "YouVe 
40 over S9, old man, and this receiver has a 
very scotch S-meter." In case you don't 
completely comprehend all this, please 
don't feel too badly, for there are quite a 
few young hams - and a few oldtimers — 
who don't dig this "dB" stuff too well. 
Years ago, when I was a newcomer to 
amateur radio, the subject appeared fasci- 
nating, and equally incomprehensible, 

For simplicity's sake, let us confine our 
remarks to decibels (dB, to abbreviate 
correctly) that deal with power ratios. 
Decibels expressed in voltage ratios may be 



of interest to phone company personnel, 
but most ham operators are thinking of 
their rf output , or lack of it, and that's 
measurable in watts. We can generalize by 
stating that the decibel is a nonlinear, or 
logarithmic, concept. Let's take a specific 
example. A 100W signal shall be our norm. 
On this basis we can run up the signal by 
+10 dB, and we now have a 1000W signal. 
Okay so far? By the same token if we 
reduce power to 10W from our 100W 
norm; we have gone down by 10 dB. 

A little bit of history in the matter may 
set things into better perspective- The bel is 
a sound power unit, originated by the 
telephone company people. Clumsy in size, 
it got cut down to a more reasonable size 
of 1/10 bel, or decibel. One decibel is the 
smallest amount of difference in sound 
power that can be recognized by the 
trained ear on a wire circuit having normal 
characteristics- Generally speaking, the rf 
transmission of power through the air 
involves fading, atmospherics and inter- 
ference. Due to this combination of QSB, 
QRN, and QRM it is generally acknow- 
ledged that it takes 3 dB of power change 
(either up or down) to be noticeable. A 3 
dB change in power can be noticed by an 
experienced operator; this would involve a 
2 to 1 change in power, that is either in 
increase or a decrease. 

After reading all this jazz in textbooks, 
handbooks, and hearing about it over the 
air, I grabbed hold of a war-weary surplus 
VariaCj and one of the 40 meter ARC-5 
"Command" transmitters, I then pro- 
ceeded to contact a friendly ham about 
8-10 miles away. This was strictly ground- 
wave stuff, and to make sure of stable 
conditions, the QSO was held at 2:30 in 
the afternoon of an early summer day. The 
DX was all of 10 miles maximum, as 
previously mentioned, and most of this was 
over water, With a little patience, we 
spotted a clear frequency, and proceeded 
to run the power level up and down. The 
ham at the other end was very helpful. You 
know what happened? He consistently gave 
me reports which closely agreed with all 
that stuff in the theory books. All the 
results were written down in an old log- 
book, almost twenty years ago. 



46 



73 MAGAZINE 




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"Northern California's Most Complete Ham Store" 95128 



With, respect to RST reports, just 
remember that most hams agree that one 
S-unit involves a power change of roughly 
6 decibels. That is, a 100W rig would have 
to go up to 400W to get a 6 dB change 
upward. Each time the power doubled, we 
add 3 dB to our calculations. The first 
increase from 100 to 200W netted a +3 dB, 
and doubling again from 200 to 400W 
added another 3 dB to the signal. Results: 
power quadrupled, and signal reports up by 
one S-unit. Sometimes it makes you 
wonder if antenna work might not pay off 
better, doesn't it? 

Another way of looking at the whole 
darned argument is to think about the big 
money makers in radio, the broadcasters. 
When a station owner or manager has the 
opportunity to increase his power, does he 
go for an increase of 100%? He does not! 
He wants to be noticeably louder, so that 
he can sell all those prospective sponsors 
the idea that he is now "much louder." 
The way it's generally done is to run the 1 
kW broadcast rig up to 5 kW - or the 10 
kW outfit goes to 50 kW. These station 
management people are in it for money — 



that's the name of the game — and to 
make a "noticeable improvement" in their 
signal strength, they usually go up in power 
by approximately 5 times. This roughJy 
coincides with our illustration above, 
whereby the I00W ham rig is increased to 
400W to get an S7 signal report up to S8. 
A quick summary. Doubling (or halving) 
power gives us a 3 dB change. Making a 4x 
change — either way — gives us a 6 dB 
change, or one S-unit. Running a IO0W rig 
up to 1 kW will give a 10 dB gain in power. 
This amounts to an increase in S-meter 
reading of about 1 .6 units. To put it in a 

humorous vein, the poor little ham with 
100W of power is way behind the com- 
mercial station running 10 kW. . .or is he? 
Look at it this way: There is a difference of 

10 dB between lOOWand 1000W. Another 
10 dB difference between 1000W and 10 
kW. That's a 20 dB total difference. But in 
S-units it only figures out to be about 3.3 
S-points on our meter (that is, if you figure 
6 dB to each S-meter unit). This may seem 
startling, but that's the way it is! 

. . . W20LU ■ 



I 
I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

■ 

I 

I 

I 

I 

I 

I 







MAY 1970 



47 




Chuck Laufman K2JLD 
42-32 215 Street 
Bay side NY 11361 



HAM STYLE 




Each month I see announcements about 
stolen mobile ri^s. Until recently the 

only deterrent to auto burglars which 1 
used, was a warning sticker and a fake 
key-actuated switch on the side of my car. 
Several weeks ago I took the mobile rig 
into the shack for a much needed overhaul, 
leaving a Heath swr bridge on the floor of 
the car, where it couldn't be easily seen. 
The car was parked right in front of my 
house^ and I confidently went about work- 
ing on the transceiver knowing full well 
that no self-respecting thief would bother 
my four-door hardtop for the price of an 
swr bridge. The fact that my car needed 
greater protection was brought home to me 
the next morning when I discovered that 
my bridge was gone. The crook had 
wedged a coathanger between the front 
and rear door windows and used it to pry 
up the door-locking button, I installed the 
alarm described in this article, and it has 
proved very satisfactory to date. It can be 
duplicated for about $5 (and even less if 
you have a well stocked junkbox). The 
alarm wilt cause your car horn to beep on 
and off if a door or the hood or trunk 
compartments are opened, and the horn 
will continue beeping until you reset the 
alarm. 

The sensing devices used are the car*s 
own door light switches. The contacts of 



these switches are easy to reach and pro- 
vide a convenient place to tap power for 
the alarm. These switches can turn on your 
alarm and still be used in their intended 
manner. If your car's rear doors are not 
equipped with these button switches, you 
may add them by drilling the appropriate 
sized holes, and mounting them by the rear 
doors in the same way as the front 
switches. At the same time you should 
mount one in the hood compartment and 
one in the trunk and wire these in parallel 
with the others. They should, of course, be 
positioned so that they are controlled by 
opening and closing these compartments. 
These switches cost about 50 or 60 cents at 
your favorite auto supply shop. You will 
have to unscrew some of your car's interior 
molding or trim, and feed the wires under 
the carpeting of the car. When you are 
done, opening any of the doors, the trunk, 
or the hood should cause the interior lights 
to go on. 

The master control on/off switch is 
usually a key operated one, and may be 
purchased from Lafayette radio for a few 
dollars. It should be mounted convenient 
to the driver's door, and it is best to locate 
it so that is is covered on the inside by 
some sort of trim, so that one cannot just 
open the door and rip out the wiring. I was 
la?y and installed mine in the trunk com- 



48 



73 MAGAZINE 



partment, but this is not a good practice. If 
you are super cheap you can u£e a single- 
pole toggle switch and mount it inside the 
door to the gas filler cap, where it won't be 
seen. Some people have suggested that a 
spark from the switch could ignite gas 
fumes, but 99% of the time there is 'no 
current going through the switch when it is 
being thrown. (But stand by for that last 



CAR WIRING 




CAR DOOR SWITCHES 

TRUNK AND HOOD SWITCHES 



V^T7 




£ 



} 



t S3 \ 



S4 



S5 




01 



3! 2 
< O— 



COURTESY 

LIGHT 



I 



KSI 



: 



i JT 

\ KEY-ACTUATED 



RELAY 
COIL 

Si 






-4rCAR 
-^"SAT 



/77 




HORN 
SWITCH 



SWITCH 



HORN 



<E> 



i 

i 
j 



HEAVY-DUTY AUTO EMERGENCY 
I LIGHT FLASHER 



Sl } S2 Car door switches 

S3 t S4 Additional switches for trunk and hood 

S5, S6 Relay contacts. 

KS, Key-actuated switch 

F Heavy-duty auto emergency light flasher 



hundredth. -Ed.) A popular spot for the 
key-actuated switch is behind the head- 
lights on the front fender. 

And now, about the circuit. As you can 
see from the diagram, the door light 
switches will supply 12V to the interior 
lights when the car door is opened. They 
can also provide 1 2V to turn on the dpdt 
relay. Contact with these switches is best 
made by removing one of the switches 
from its mounting and tapping into the 
wires connected to it, using wire nuts, 
When the relay is actuated by these 
switches, one set of its contacts closes and 
is connected so as to provide continuous 
voltage to the relay coil even after the door 
switch is turned off. Only turning off the 
main switch will release the relay. The 
other set of contacts on the relay goes in 
parallel with the horn switch. The wires 
from this switch can be traced from the 
steering column. When the relay is acti- 
vated the horn will go on. The heavy-duty 
emergency flasher is used to make the horn 
blast on and off, a distinctive sound which 



will tell you that you are hearing your car, 
and not just another irate motorist. 

Any type of 6 or 12V dpdt relay will 
serve this purpose, providing the contacts 
aren't too small. I used one which was 
mounted on an octal base, and mounted 
the whole assembly on an L bracket under 
the dashboard. There is nothing critical 
about the construction. Details of feeding 
the wires through the car and opening your 
car's interior moulding will vary with the 
particular can 

There are several drawbacks to this 
particular system, the main one being that 
if your car is tampered with and you aren't 
around, chances are good that you'll wind 
up with a dead battery. But, into each life 
a little drain must fall. It's very easy, of 
course, for the thief to open your hood 
and disconnect the two horns when he 
hears them go off. With a little ingenuity 
you can make this inconvenient for him. 
Or, buy a used horn from your local 
junkyard and mount it in or under your 
trunk, and wire it in parallel with the 
others. Your unwanted friend will go crazy 
trying to find it, and this will also make a 
good warning signal for those nasty people 
who are always standing in back of your 
car when you have to back up. Some bad 
guys like to get under your car and cut 
your battery cable before the alarm goes 
off* You can cover your battery cables 
with shielding from BX cable. It is flexible 
and can only be cut with a hacksaw. Only 
the very hippest auto burglars carry hack- 
saws. 

There are many other variations and 
sophistications for this alarm system, 
including a tape-recorded message which 
tells the guy what you think of him. With a 
little effort all the headlights can be made 
to go on and off. To complete the job, a 
few warning stickers can be added to your 
windows and the door-lock buttons can be 
changed to smooth cylindrical types which 
can't be pried up from the outside. There is 
practically no limit to what you can do. 
But remember, no matter what you design, 
there is a thief somewhere who, if he really 
wants to, can still get around any alarm 
system. 

. . . K2JLD* 



MAY 1970 



49 



POWER 





from. 
C€M£I 9 OJVEJVTS 



This article originally began as a brief 
description of a small power supply 
intended to deliver 22 Vi volts at a few 
milliamperes for a transistorized preampli- 
fier. However, because of the wide variations 
of the components available and the desires 
of builders, it was decided to extend this 
article into as complete a description as 




possible of power supplies in general. The 
main objective, of course, is to allow the 
builder to design his own power supply to fit 
his own needs. However, it is strongly felt 
that most readers will want to know what 
they are doing, even if they can do it quite 
well. It is for this purpose that all attempts 
have been made to include explanations or 
derivations wherever it is possible, especially 



Clifford Klinert WB6BIH 
520 Division Street 
National City, CA 92050 

where a concept is so logical and uncompli- 
cated that it is easier to simply know why or 
how it works rather than to memorize 
meaningless formulas or circuits. So, actually 
this project had a much earlier beginning, 
with the destruction of about ten dollars* 
worth of silicon diodes. Its final success was 
achieved after a college course in electronics 
engineering, and the most useful information 
is described in this article. 

The Transformer 

If the builder has an adequate power 
transformer for the desired project, he might 
skip this section. However, the desired volt- 
ages at the desired prices are not always 
available, and if the power requirements are 



t 

I 



PRIMARY 
9000^. 



o- 



5EC0NDARY 
600 S\ 



v 2 

i 



Fig. 1* Schematic of a typical audio trans- 
former and Its parameters. 

small, an interesting substitution can be 
made. 

Several audio output transformers were 
obtained from surplus, but they all had a 
600 ohm output impedance, and were unfit 
for driving a speaker. At the same time a six 
transistor audio preamplifier was hungrily 
earing up 22Vi volt batteries. It soon became 
apparent that the cost of replacing batteries 
could easily exceed the cost of the preamp. 
Store-bought power transformers are also 
costly, compared to the low priced epoxy 



50 



73 MAGAZINE 



transistors. It was finally decided to try an 
experiment. 

A schematic of a typical transformer and 
its parameters is shown in Fig, 1. By 
assuming the transformer to be 100% effi- 
cient* we write the equation for the power in 
the primary and secondary. 



P = P = I Z 



(1) 



The subscript 1 indicates primary, and the 2 
indicates a secondary parameter. Equation 
one says that the power in the primary 
equals the power in the secondary, which is 



Tl 



1 15 VAC 

RMS 



W%^- 

29 3 VAC 
RMS 



0| 



-o 4- 



Cf 



R| 



o — 



Fig. 2, Half-wave rectifier circuit. 

equal to the current squared multiplied by 
the impedance. If we now use algebra, and 
divide equation one by Z t and I 2 , equation 

two will result. 

Z- 

^- (2) 



I 2 



V 



1 



Now the impedance ratio is expressed in 
terms of the currents* Since we know that 
current is voltage divided by impedance, a 
substitution can be made for l t and I 2 . 



T 2 
l 2 



V 2 

V. 2 



I 2 ^1 z 



(3) 



zt 2 



1 



By manipulation of equation three (dividing 
it out), equation four is obtained. 

— (4) 



V 2 Z^ 2 

v 1 ^2 = 



Z 1 2 V 2 2 



1 



If equation four is now divided by Z 2 2 , and 
then multiplied by Z 2 2 , the final result is 
obtained. 2 

^r = — (5) 

v 2 2 z 2 

Now that equation five is established, it is 
possible to find the voltage ratio in terms of 
the impedance ratio. 

This derivation was given to show how 
equation five could be obtained if it were 
forgotten or was unavailable. This is 
assuming Ohm's law is known and a knowl- 
edge of basic algebra is available. 



Equation five can be made more useful 
by dividing both sides by V^, and inverting 

the result. 

Z 2 V t 2 



v 2 = 

v 2 



(6) 



1 



To obtain V 2 , we take the square root of 
both sides of equation six. 



V 



2- 




(7) 



Equation seven is the final result, and the 
output voltage of our transformer can now 
be found, 

Vj is 115 volts, the line voltage, and Z 2 
and Z t are 600 and 9,000 ohms, respec- 
tively . Plugging these values into the formula 
we get: 



V- 



i 



(It 5 ) 2 (600) 



9,000 



= 29.3 volts (8) 



Thus, if 115 volts is put into the primary, 
29.3 volts will come out the other end, and 
it can be rectified and dropped down to 22^2 
volts. 

Designing the Rectifier 

There are two primary factors that work 
together to destroy silicon diodes; excessive 
voltage and excessive current An example of 
each of the most common circuits will be 
discussed, and the ratings required for the 
diodes will be determined. 

The simplest rectifier is the half- wave 
circuit shown in Fig, 2, Assuming that the 
reader is familiar with this circuit, we shall 
proceed to find the peak inverse voltage, or 
P1V required for the diode. Since the RMS, 
or effective voltage, is given for the trans- 
former, the peak voltage must be found. The 
reader must remember that this is a sine- 
wave voltage where the voltage varies from 
zero to some positive peak value, goes back 
to zero, goes to a negative peak value, and 
finally back to zero sixty times each second. 
A complete mathematical proof would re- 
quire the use of calculus which is beyond the 
scope of this article, but a reference is 
given. 1 

The peak voltage at the secondary of the 
transformer is the effective voltage multi- 
plied by the square root of two, 

a (9) 

V2 x V 2 = 1.414 x 29.3 - 41.4 volts peak. 



MAY 1970 



51 



Lets assume that Rj in Fig. 2 has so 
high a resistance that Ci charges up com- 
pletely to the peak voltage, 4L4 volts, and 
does not discharge. Also, we shall assume 
that the top of the transformer secondary 
winding has reached its peak negative value 
of -4L4 volts. By adding the voltages, we 
can obtain the equivalent circuit of Fig. 3, 



FROM 7 1 



rrn 

>I 



FROM C| 



414 
VOLTS 



i 

"="414 



^ VOLTS 



J" 



rH|»[»hhr 



82 6 
VOLTS 



Fig, 3. PI V equivalent circuit. 



across 41.4 volts for a very short period of 
time. If R 2 is a small resistance, a high 
current will be forced through the diode. 
This is the reason a resistor is usually seen in 
series with diodes in a power supply, Since 
the internal resistance of the diode is usually 
very small, it is assumed to be zero, and a 
resistor is inserted in series to take up the 
surge. The resistance is determined by Ohm*s 
law, with knowledge of the peak secondary 
voltage of T x> and the allowable surge 
current, R 2 is usually somewhere between 
20 and 40 ohms, so by picking a value, say 
30 ohms, we can find the allowable surge 
current. By plugging values into the fol- 
lowing formula we get: 

(10) 
V 41.4 



I = 



R 



30 



= 1.38 amperes surge. 



with 82.8 volts across the diode in the 
reverse direction. Recall that conventional 
current is from + to - in the circuit con- 
nected to the voltage source. Since current 
flows in the diode in the direction of the 
arrow, if current were flowing in the diode, 
it would be in the reverse, or inverse 
direction. This indicates a peak inverse 
voltage of 82.8 volts in this case. To survive, 
the diode would have to have a PIVof 82.8 
or more volts. We always design equipment 
with a safety factor to prevent unexpected 
changes. If a safety factor of 50% were used, 
50% or 82.8, or 41.4 would be added to 
82.8, giving 124.2 or more volts as the 
desired voltage requirement. 

The current rating that is most often 
given for a silicon diode is for the current 
that it will be passing under normal con- 
tinuous operation. A safety factor should 
also be included here, but there are much 
higher currents that are present only for a 
short period of time. Suppose now, that the 
circuit of Fig, 2 has been turned off for a 
long period of time. Ci will be completely 
discharged by Rj* Assume that the circuit is 
turned on at the instant in the ac cycle so 
that a positive peak voltage suddenly appears 
at the top of the secondary winding of T t . 
Since we know that the voltage across a 
capacitor cannot change instantaneously , the 
capacitor will appear as a short circuit for an 
instant. In effect, R 2 an ^ ®i w iU be in series 



Now, this is a relatively low surge current 
because diodes with a few hundred mOli- 
amperes of continuous forward current 
rating can have a surge current of ten to 
twenty amperes or more. 




r^E 



— o + 



-0- 



Fig. 4. Full-wave center-tapped rectifier. 

Figure 4 shows the full-wave rectifier. Of 
course, this circuit can only be used with a 
center tapped secondary, so it would be 
useless with the transformer that was avail- 
able. It gives a smoother output waveform 
that is easier to filter, and a short discussion 
of the PIV should be included. 

Figure 4 is a familiar circuit, and just a 
glance will show that it is actually two 
half-wave rectifiers fed 180° out of phase by 
the transformer. The output is connected in 
parallel across Ci and R^ As in Fig. 2, 
the peak inverse voltage is twice the peak 
value of each half of the secondary plus a 
safety factor. The reader should go through 
Fig. 4 as we did with Fig. 2 to satisfy himself 
that the result for the PIV is correct. Also, 
the surge current can be determined in a 
similar manner as was done for the circuit of 
Fig. 2. 



52 



73 MAGAZINE 





Supplier- as shown by prior ads 

Ham Radio Magazine Feb. 1970 
"73" Magazine March 1970 






99 



it 



73" Magazine April 1970 
73" Magazine May 1970 







THIS MONTH ONLY -May 1 to 31, 1970 

or until out of stock 

LIMITED SUPPLY 








U44BBT -450 MHz 18 watts 
T-power S84.50 w/accessories 



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IN APPRECIATION OF OUR CUSTOMERS' PAST SUPPORT 

REMEMBER - AMATEURS ONLY and FOR AMATEUR USE ONLY 

PLEASE SUPPLY YOUR CALL LETTER WITH CORRESPONDENCE 

OPEN - 9:30 to 6:00 FRIDAY NIGHT till 8:00 
CLOSED - SUNDAY, MONDAY and HOLIDAYS 

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SPECTRONICS 



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The FM People 

GARFIELD AVE. OAK PARK, ILL 



60304 



Now, we turn to the circuit of Fig. 5, 
which is the circuit most likely to be used 
for the application we desire, In order to 



115 VftC 
RMS 






O + 



o- 



Fig. 5* Full-wave bridge rectifier. 

study this circuit it will have to be divided 
into two parts, one for the positive, and one 
for the negative half-cycle of the ac voltage. 



T| 



O- 



Vp£AK 




o + 



Fig. 6. Positive half cycle of the full-wave 
bridge rectifier. 

Fig. 6 shows the half-cycle in which the top 
of the secondary of Ti is positive. Note that 
the diodes that do not conduct are omitted 
from Fig. 6 because they act as open 
circuits. We now have a much clearer simpli- 
fied circuit that will show how the full wave 
bridge works. R 2 is the surge limiting resis- 
tor and will have a value of: 



peak 



I 



= R^ (surge resistance). ( 1 1 ) 



surge 



Vpeak is the peak voltage at the secondary 
of T t , and since the diodes act as direct 
shorts, a current, I, will flow through the 
diodes, R 2 , and R 1? and C t . Also note that 
C A is considered to be a short circuit for the 
surge calculations as was done before. I S urge 
is the allowable surge current that passes 
through the diodes if the circuit is turned on 
at a voltage peak. The reader has probably 
noticed that since the diodes offer a short 
circuit during the half-cycle that is being 
described, a dc voltage will be generated 
across Rl and CI that will become the 
output voltage, V^c* Now, take a look at 
Fig. 7, the negative half-cycle simplified 

circuit. If the reader traces the path that 
the current travels through D 3? D 4 , Rj , and 
R 2 , it is easy to see that this is the correct 



equivalent circuit. In fact, Fig. 7 is just Fig. 
6 turned upside down when the transformer 
polarity changes and the diodes act as a 
double-pole double-throw switch to keep the 




Fig* 7, Negative half cycle of the full-wave 
bridge rectifier. 



current flowing through the load (Rj and 
Ci ) in the same direction in both half-cycles. 
To find the PIV for each diode, assume 
that the secondary of T x in Fig. 7 is at its 
peak voltage in the opposite polarity . Also 
assume that Cj is charged to the peak 
voltage of T x , and there is no voltage drop in 
the diodes or R 2 - The voltage drop will be 
small because the current is small. Now, 
showing only the diodes and the voltages, we 

have the equivalent circuit of Fig. 8. This 
shows how the voltages add to make up the 
maximum peak voltages across the diodes in 
the reverse direction. Since there are two 
diodes, the voltage divides equally between 
them 2 , and the voltage across them is 
^peak This is one-half of the voltage of the 
diodes in Fig. 4, so lower PIV diodes 
may be used, but twice as many are needed. 

If the same transformer is used, the peak 
voltage (from equation nine) is 4L4 volts 
plus a 50% safety factor. The PIV would 
have to be at least 41.4 + 20,7=62.1 volts 
peak. 

If diodes are to be placed in series to 
obtain a higher overall PIV rating, something 
must be done to equalize the voltage drop 
across each diode. All diodes are different* 
and one will pull more current than another, 
resulting in one diode having a large voltage 
across it which causes it to break down and 
short out, throwing all the voltage across the 
other diode, or diodes, and eventually the 
whole string of diodes is destroyed. This was 
a common happening when the builder was 
unaware of the real meaning of PIV. Since 
they short out rather than burn open, the 



54 



73 MAGAZINE 



transformer can be burned out if it is not 
fused. 

To prevent this, voltage dividers can be 
placed across the diodes to provide equaliza- 
tion. Since the diode is operating in its 
reverse direction, (very, very small current 
flow) the internal resistance of each diode is 
very high, and resistors between 100K ohms 
and 500K ohms can be used across the 
diodes to provide equalization, 220K ohms 
is a typical value. Capacitors across the 
diodes can also be used, but can be more 
expensive. One should be careful to calculate 
the required power or voltage rating for the 
type of equalization system to be used. It 
should be noted here that it is often less 
expensive to use higher PIV diodes and 
fewer resistors, particularly when inexpen- 
sive surplus diodes are used. 3 Determine the 
cost per PIV ratio for each kind of diode, 
and be sure to include the cost of equalizing 
resistors when making the choice. 

Filters 

The value of filter capacitors and chokes, 
and the size of the load will in general 
determine the output voltage and ripple 

content. This is, of course, depending upon 
the type of circuit and transformer used. It 
is possible to calculate these values, but a 
number of factors are listed that would 
preclude a detailed discussion of this, 

1 , Very precise results are usually not neces- 
sary in amateur work, 

2, Any parts that are available will probably 
be used if they look as if they will work, 
regardless of their values, 

3, The actual value of a commercially made 
electrolytic capacitor may vary by as much 
as 60% from its marked value (check the 
label). 

4, No serious damage will result from exper- 
imentation so long as the voltage ratings are 
adequate, 

5, It's easier to put it together and try it 
than figure it out, in most applications, and 
more reliable (no math errors). 

Also, it should be noted that charts and 
graphs are available which can give a rough 
idea of what the ripple content from a 
certain type of rectifier will be, 4 

Final Comments 

The circuit of Fig. 5 was used in the 



power supply shown in the picture. The 

filter system used a capacitor input system 
with capacitances of 40 juF and a choke 
of unknown value. The diodes were lN92s 
with a PIV of 200 volts and a 25 ampere 
surge rating. The continuous current rating 
was 100 mF, so all ratings were adequate. 
It works very well. 



* 



V FROM ~± 
T, PEAK — 



— Vpc PEAK 






£ 



ZL 



A 



— V FftOM T) PEAK 
T - V DC reA * 



— Voc PEAX 



* 



2 * Vdc " 
PEAK 



°4 



L'.5 



Fig, 8, PIV equivalent circuits. 

The main objective of this discussion has 
been to provide information that can be 
used to safely construct any type of power 
supply from whatever components are avail- 
able, and little emphasis was placed on any 
particular circuit or design. It was decided to 
use this approach to allow the reader to 
design his own power supply rather than 
having to dig through countless articles to 
find one that will give him what he wants 
that he can build with the components that 
he has on hand. Also, the reader appreciates 
the satisfaction to not only design his own 
equipment, but to actually know how and 
why it behaves as it does, 

. . . WB6BIH" 

References: 

L Fitzgerald, Higginbotham, and Grabel, 
Basic Electrical Engineering, McGraw-Hill. 
See page 138 to prove equation nine. 

2. If resistors are placed across each diode. 
Go back and keep reading. 

3. Such as Solid State Sales or Poly Paks. 
See the ads in the back of this issue after 
going back to read the rest of the article. 

4. ARRL, The Radio Amateur's Handbook, 
Newington, Ct. See page 307 for filters. 



MAY 1970 



55 



SHARP AS A LASER 






THE SWAN MODEL SS-16 
QUARTZ FILTER NETWORK 







■mil 



Now available to provide super 
selectivity for your Swan Trans- 
ceiver. Easily installed in models 
240, 260, 270, 350, 350C, 400, 500, 
and 500 C. 

• Unprecedented rejection of ad- 
jacent channel QRM. 

• 2.7 kc bandwidth at 6 db down, 

• Shape factor 1.28. 

• Ultimate rejection: 140 db. 

• 16 poles. 16 precision crystals 
in a lattice filter network. 

• Sideband suppression: 80 db. 

• Carrier suppression: 45 db with 
the filter alone, plus approxi- 
mately 40 db more from the 
balanced modulator. 

• Mounting: Same as standard 
Swan filter, but taller. 






\ 



Jk 



a 






Price: ... $95 

wifh instructions. Specify 
transceiver model. 

See your Swan dealer today. 





ELECTRON ICS 



305 Airport Road 

Oceanside, California 92054 

A Subsidiary of Cubic Corporation 




Selectivity has come 
a long way. 



Today we take tor granted shape factors and 
ultimate rejection figures that were consid- 
ered either impossible or extremely expen- 
sive twenty years ago. Practically all single 
sideband equipment has a pretty good filter 
network in the L F. system to establish the 
selectivity pattern. It may be a high frequency 
crystal lattice network, or the lower frequency 
mechanical type. 

There are three factors about the I. F. filter 
that determine how well it will do its job. 
The one most commonly recognized is the 

width of the passband, usually measured at 
a point 6 db down from minimum attenuation* 

This bandwidth is what determines the audio 
frequency range you can transmit and receive 
through the filter. The wider the passband, 
the wider the range of A.F. It becomes neces- 
sary, of course, to choose a happy compro- 
mise between a narrow bandwidth to help 
reduce QRM, and a wide bandwidth which 
will provide more natural sounding voice 
quality; You'll find that the Swan filter has a 
2.7 kc bandwidth. This gets us into another 
subject which we'll discuss another time. 

Shape factor is the next consideration in 
measuring a filter's quality. This is the ratio 
between bandwidth at 60 db and 6 db down, 
and is a measure of how steep the attenuation 
curve is outside the passband. This factor is 
often referred to as "skirt selectivity/' The 
narrower the passband at 60 db down, the 
better the filter will attenuate strong adja- 
cent channel signals. A good crystal lattice 
filter will have a shape factor of 1.7 to 2,0 
depending on its center frequency. Best shape 
factors are achieved right around 5 mc, which 
is one of the important reasons for Swan's 
LF. system being at 5.5 mc On the other 
hand, the lower frequency mechanical fil- 
ters don't have quite as good a shape factor 
as high frequency crystal filters, a fact which 
isn't very well known, and may come as a 
surprise to many. 

Ultimate rejection is the third, but certainly 
not the least important measure of how good 
the filter is. All filters eventually "flare-out" 
at the base of their attenuation curve, This 
tells you how much the filter will attenuate 
signals which are 10 or more kilocycles out- 
side the passband. If you have a base attenu- 



ation level which is down 80 db, for example, 
a strong local signal may very well come 
through the receiver over quite a large por- 
tion of the band, and it won't be his fault! 
There's no point in telling him how broad he 
is if it's your filter that's falling down on the 
job. A good high frequency crystal filter hav- 
ing 6 or 8 poles will reach ultimate rejection 
levels of 100 db, or more/Here again, filters 
in the 5 mc region are better. So, all you 
happy Swan owners may as well know the 
facts and blow your horn a little. CF Networks 
has made that beautiful precision filter that's 
installed in your rig, and it's really a dandy. 

The accompanying graph illustrates clearly 
what we've been talking about But so far 
we've only been discussing the "standard" 
Swan filter, and comparing it with other typi- 
cal 9 mc crystal filters and 455 kc mechanical 
filters. In case you hadn't noticed, there's a 
tall, skinny curve on the graph that's all alone. 
This is the new SS-16! Made exclusively for 
Swan by CF Networks, this 16 pole quartz 
filter network establishes a new standard of 
comparison- Shape factor of 1.28, ultimate re- 
jection greater than 140 db! A giant QRM 
killer, the SS-16 wipes out strong adjacent 
channel interference with unprecedented at- 
tenuation. And in transmit mode, unwanted 
sideband and carrier suppression are both 
increased greatly. For a new experience in 
Super Selectivity, install the SS-16 in your 
Swan Transceiver. They are available for the 
current 5.5 mc, I.F., or the earlier 5.175 mc 
I. F. system. Installation and adjustment is 
quite simple, and our famous customer serv- 
ice department is, of course, available for 
assistance if required. 

Sorry, the SS-16 is only available for Swan 

transceivers. 

73 





E L ECTRO N I C S 

For better ideas 
in amateur radio. 

305 Airport Road 

Oceanside, California 92054 

A Subsidiary of Cubic Corporation 








eing an electrical engineer and a ham* 1 

have for many years maintained the 

one-eyed "Gooneybox," Gonset 6 meter 

Com mimical or in my cars, changing every 
year or so to a newer model car and with 
the change, moving all the ham gear into 
the new ear. 

For years. 1 had no trouble changing the 
rig from one car to the next until lasi 
December when I leased a 1969 "loaded* 1 
Buiek Riviera. This ear is truly a beautiful 
* 'mechanism" and I could hardly wait till I 
could transfer the "Halo/' install the 
Communicator, and start transmitting. The 
Communicator fitted well over the hump 
of the transmission - and, after attaching 
the coax, I started up the engine and 
turned on the rig, I was greeted with a 
noise level like nothing 1 had heard before. 
I might as well sit beside the battleship 
Wisconsin while she fires a broadside. 1 was 
unable to hear a thing! I was getting hash 
which sounded like it was about 80-100 
Hz. There must be something wrong with 
my rig, I deduced! After all the years it has 
been in use. it probably has blown its cool, 
I turned off the engine and the noise level 
went away. Nothing serious. Something 



Yale Saffro K9BDJ 
7841 Kildare 
Skokie IL 60076 





probably was not grounded properly. 

For the next five days I bonded, sealed, 
and tightened every possible joint and 
connection. But the noise was still I here 
when I turned the engine on. 

Several months passed and it was in the 
spring that I finally wrote the Buiek people 
explaining my problem. It took 1 Vi months 
lor them to come up with an answer which 
I had already tried. I had reached an 
impasse! 

Again, I surveyed the entire car and 
tested for various "leaks, *" searching with a 
"sniffer, 11 Sure, 1 could pin down the area 
of the noise; but now, while the engine was 
running I had, one-by-one, disconnected 
just about everything - yet the noise per- 
sisted, 

More months went by and by this time I 
was getting old and feeble and ray "Riv" 
still had not stopped "generating" a noise. 
Then, sitting down in the car one day, I 
started the rusty brain clicking. Why was 
my car different? What did my car have 
that made it so different? What was it that 
pulsed or vibrated even when the alter- 
nator, voltage regulator, and everything 
that could be disconnected hud been dis- 



58 



73 MAGAZINE 




The COMPLETE Code Practice System 

MOST CODE PRACTICE SYSTEMS WILL HELP YOU IMPROVE YOUR RECEIVING 
BUT HOW MANY OF THEM WILL IREALLY HELP YOUR SENDING? . . . 



THIS ONE WILL 

AND IT INCLUDES A PANASONIC 
PORTABLE CASSETTE RECORDER ! 

Practice receiving with pre-recorded cas- 

settes 

Practice sending with the built in code 

practice oscillator 

By recording your own sending, you will 
be able to spot flaws and errors that 
would ordinarily be overlooked 
When it is not being used for code 
practice, the recorder may still be used 
around the shack and for general enter- 
tainment purposes 

The system comes complete with a 1 
hour pre-recorded cassette (specify speed), 
a 1 hour blank cassette, microphone, ear- 
phone, and batteries. 




/ 



WOODSIDE CS-1 



$48.00 



Extra pre-recorded cassettes (1 hr) 

specify 8, 16, or 25 wpm . . $5.50 

Johnson heavy duty key . . . $6.50 

110 vac adaptor $7.00 

PLEASE ALLOW S3.00 FOR SHIPPING - EXCESS REFUNDED 



WOODSIDE RESEARCH CO. 



BOX 276, YARDLEY, PA. 19067 



PHONE: 215-493-5850 






COIL 

I in — -| \/4 tn 

t 




I7TURN5 #!0£NAMEL 

COPPER WIRE 



FERRATE CORE 



— 3/0 in Of A 



** — i ift 



connected? The answer came on me like a 
flash flood. 

Buick had done us Riviera owners a big 
favor: to justify increased costs, they gave 
us all a big fat juicy electric fuel pump- 
Novv all I had to do is find that stupid 
pump - the one remaining electrical 
apparatus I hadn't checked out. In years 
gone by, the purchaser of a car would 
receive a book that would tell the grease 
points, wear points, ignition points, etc.: 
so, easing my hand into the glove compart- 
ment (it is so small you have to slide your 
hand in)/ I grabbed my instruction book 
with the tips of my fingers and sJowly 
pulled the book out so as not to tear off 
the top skin of my hand, I scanned the 
book. No index, and no mention of a fuel 
pump, either electrical or vacuum. 

I called all my engineer friends over to 



the house for |>eer and help, and we all 
started to slowly circle the car, each trying 
to come up with a solution. Where was that 
furshluggincr pump? Here we were, six 
engineers - and no one could even suggest 
where we might find the fuel pump. 
Finally, someone suggested it might be 
under the trunk floor — only as a despera- 
tion move, we looked. And sure enough, 
there it was. , . a black Bakelite cap with a 
blue and a brown wire coming from it and 
heading in the general direction of the 
front of the car. 

Back down into the shuck we went to 
make up a low-impedance coil, but here we 
had one problem. By this time, the brew 
had us slightly staggering and no one could 
read the grid dip meters. But after a couple 
of hours we did manage to make up a coih 
After it was installed, I started the engine 
and turned the Gooneybox on... Voila! li 
worked, and I immediately made a contact 
with a ham about 30 miles away. No more 



-u' h t 



But where are the 6 meter hams? The 
band is dead here now! 

. . . K^BDJ ■ 






MAY 1970 



59 



KEEP 



I 



EM 







COOL 








"KPO 




CANS" 






Douglas Byrne G3KPO 

Jersey House 

Eye, Peterborough, England 






Tubes get too hot for comfort, burn 
themselves up aplenty . . . what to do? Keep 
'em cool, boy, keep "em cool! 

Easier said than done, for while tubes get 
smaller, nobody has yet succeeded in min- 
iaturizing the watt. Of course, you can use a 
blower, but that brings with it problems of 
vibration and noise, both mechanical and 
electrical. 

So let's see if we can't get that unwanted 
heat away much more efficiently by the 
normal method of radiation and convection— 
with the aid of flappy tailfins! No noise, 
nothing to wear out, and best of all-no cost 
- . . here's how # 

Heat is extracted from the tube by a 
special heat-dissipating shield made up of a 
series of individual tin plates shaped as 
shown in Fig. L End D has direct thermal 
contact with the tube body, extracting heat 
by conduction, transferring it to end E, 



60 



where the heat is removed by radiation and 
convection of the circulating air. 






E 



B C 



D 



A 

Fig. h An individual plate. 



To make, you need to cut a half-dozen or 
so small sheets of fairly flexible sheet metal 
(2% x 4 in. will be about the right size for 
the usual PA tube). 

73 MAGAZINE 




Snip a slot in each plate as at A in Fig. 1 5 
and a few more as at B and C— cut each slot 
sufficiently wide and deep for A of one plate 
to slide easily in B or C of the next, the 
bottom and tops being level with each other. 

To assemble the thing, slide slot A of one 
plate into slot B or C of another. Continue 
until you have a circle of plates, with an 
opening in the center for the tube and the 
flappy tailfins sticking out all around. 

Paint all fins flat black. Black has a 
heat-absorption characteristic and will 
enhance the overall efficiency of your dissi- 
pator. 




Fig, 2. Plan view of complete shield on tube. 



Now try it on for size. If slightly out. 
select slots B of C as appropriate. If much 
too large, cut a new slot. Slide over tube and 
bend or cut tailfins to avoid nearby com- 
ponents. 

A secondary benefit of the shield is that 
it will reduce direct radiation of heat onto 
such things as vfo coils and electrolytic 
capacitors, where it is definitely NOT 
wanted. 

A good point to remember is that not all 
circuits will be able to tolerate the lube 
capacitance introduced by the shield. Some 
experimentation is warranted in most cases, 
Retuning will be required in virtually every 



case 



. . . G 3K.FO 



LINEAR AMPLIFIERS 

PER POUND 



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sion • Operating convenience * Eimac 3-1000Z 
• ALC • Fast acting overload protection * 80 
through 10 meters • Prestige styling • Adequate 
cooling, even on a continuous use basis. 



BTI LK-2000 ...For 

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Price .... $89500 



Writ* for free brochure or send 
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manual. 

BTI AMATEUR DIVISION 

Hafstrom Technical Products 

4616 Santa Fe. San Diego, Co. 92109 





SWAN 
BAND PASS ANTENNAS 





Return Loss Response Band Pass Response 



50 MHz to 52.5 MHz 

8 element- 12 dB 
142.5Hz to 149 MHz 

7 element - 10 dB 

9 element - 13 dB 
11 element - 15 dB 

220 MHz to 225 MHz 
9 element - 12 dB 



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..$14.95 
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. . $24.95 

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420 MHz to 450 MHz 
*12 full wave elements-12 dB . .$14.95 
*21 full wave elements-14 dB . .$29.95 
(*each is 2 antennas side by side) 

Baluns for above antennas ea. . $ 5.00 

All prices FOB STOCKTON, CALIF. 

ORDER FROM: 

SWAN ANTENNA CO. 

646 N. Union - Box 1 122 Ph. 464-9897 
Stockton, California 95201 






MAY 1970 



61 



— i 



TOWARDS 
AN IDEAL 



STATE 



AMATEURS 



. . Breadboarding the complete IC system 



This second part of a two-article series 
on a reasonable cost, portable "ideal" 
i-f for the amateur homebrewer describes the 
design method and working breadboard 
model of the L65 MHz to 135 kHz con- 
verter module, a 135 kHz i-f filter which 
really cuts the mustard, an avc module for 
use with the Motorola HEP 590 IC i-f 
amplifier, and the results when using the 



62 



William Hoisington K1CLL 
Far Over Farm 
Peterborough NH 03458 



whole i-f system. If you like plenty of lows 
when listening on the bands, this is the unit 
for you; the bandwidth is between 3 and 4 
kHz, which is cutting it pretty close for good 
voice quality. Of course, when the going gets 
real tough, you don't care about quality, but 
you do care plenty about understanding 
what your contact says. That's when a 
narrow bandwidth really helps. 

73 MAGAZINE 




The possibilities for the homebrewer with 
this double-frequency i-f seem quite inter- 
esting; indeed, I'm anxious to get one 
packaged for myself, along with a tunable 
packaged 10 meter front end for use with 
VHF and UHF converters. 

Overall System 

Figure 1 shows the block diagram of the 
complete triple-conversion portable receiver. 
Previous articles have described detailed con- 
struction of various portions of this system. 
This section is concerned with the 1 .65 MHz 
to 135 kHz converter, the avc module, and 
the 135 kHz filter. 



article. Of course, you do have to add an 
extra winding or so, but the coil form, 
adjustable center threaded core, tuned wind- 
ing, outer powdered-iron core, and the 
aluminum case are all there. 

On the subject of mixers, be sure to read 
the "trouble" section, where it shows what 
happens when you put a high Q coil in the 
collector circuit of a lively mixer and leave 
the emitter only partly tied to ground. In 
this condition, you're in grave danger of very 
strong oscillation on 1 .65 MHz (if that is the 
frequency of the output circuit). 



■ UNITS DESCRIBED IN THIS ARTICLE 



w 



/TENMETER\ 
\ FRONT-END,/ 



CONVERTER 
XTAL CONT 



TUNEABLE 

l-F 



I 65 MHz 
l-F 



SIX, TWO 
432J296 



26 TO 30¥Hi 




CONVERTER 

I 65 MHz 
TO *35 K Hi 



■— DEMODULATOR 



AF 




Fig. i. Block diagram, ideal i-f system. 



Instead of the first crystal-controlled 
converter followed by the tunable 1 meter 
front end, you can use a tunable 6 meter job 
if you wish, resulting in a double-conversion 
receiver. You can even use it that way on 
2m, but tuning gets pretty touchy then. The 
crystal oscillator in the VHF— UHF conver- 
ters relegates the tuning business further 
down the line to the 28 MHz region, where 
it can be done in a reasonable fashion. 

Once the i-f system is packaged and 
installed in a little carrying rack along with 
the desired converter and companion solid- 
state transmitter, it should make an ex- 
tremely interesting and useful addition to 
portable amateur equipment —and at reason- 
able cost for the homebrewer. 

Mixer 

In the past I have described several 1.65 
MHz mixers, but this is the first using 
ready-made coils that you can buy on the 
market; that is, these are the Miller series, 

described in detail in the first part of this 



Various types of oscillator injections were 
tried, and the one shown in Fig. 2 is the 
result. It uses straight link coupling from the 
oscillator inductor to the mixer base coil, 
and has the nice feature that the amount of 
coupling is easily adjusted for the best 



FROM 

165 MHz 

l-F 






rh 



FROM 
\ 765 MHx 

osc 



+ 12 



L2 



L4 



m 



e 



T 



5K HEP 55 



TO 133 KHi 
l-F FILTER 
i * 



i 



50- 300 < /^ys: — f 

ffr 



L3 



<+ 



ffa 



50-300 pF 



it 



iK 



^ 




LI — 3 TURNS WIND OVER L2 

L2- MILLER 
9054 

L3- 15 TURNS WJND OVER L2 



L4 - 3 TURNS WIND OVER L2 

L5— MILLER 
9059 

LG- 3 TURNS WIND OVER L5 



Fig. 2, JL65 MHz to 135 kHz converter mixer 
detail 

effect. This is useful because if you under- 
coupie you lose gain, and if you overcouple 

you can get frequency "pull lag'* ; unwanted 






MAY 1970 



63 



harmonic power rises also. You will notice 
several windings of only 3 turns or so, which 
is a small number at an intermediate fre- 
quency. This is possible because of the 
powdered-iron cup core used, which 
increases the magnetic coupling and the Q of 
the coils. Figure 2 shows the mixer circuit 
using the Miller coils. 

Here's how it works: Signal energy from 
the 1.65 MHz i-f module comes in on LI and 
is transferred selectively to L2, and from 
there to L3, which is matched to the base 
input of QL Oscillator energy at 1.785 MHz 
is supplied also to Ql via L4, and the two 
signals are mixed, or beat, in Ql , to furnish a 
collector output on 1 35 kHz. 

The collector circuit is tuned to 135 kHz 
with a Miller 9054 inductor and a mica 
compression trimmer of 100 to 500 pF. A 
link of 3 turns is wound on top of the 9054 
winding to couple energy to the filter. The 
base and the emitter are treated in the usual 
fashion for dc bias, with the emitter heavily 
bypassed to ground, which effectively elimi- 
nates self -oscillation. 

1.785 MHz Oscillator 

The basic circuit of this oscillator has not 
been changed from that described in the first 
article, but this time it uses coils that are 
readily available. The Miller 9054 unit works 
fire with the addition of only 6 turns of 
wire to create an emitter feedback tap, as in 
Fig. 3 ? and a pickup link to transfer the 
needed energy over to the mixer. 



sure that the outer cup core stays in place 
inside the can. Figure 4 shows the oscillator 

winding details. You must get the direction 



osc 



Lf 

MILLER 9054 
INSIDE 




NE* WINDING L2.fi TURNS 

WIND ON L2 IN SAME 
DIRECTION AS LI 



NO 34 D.CC IS A GOOD 
SIZE 



START OF NEW 
WINDING 



DRILLHOLE 



Fig. 4. Oscillator coil detail, 1.785 MHz, 



of the feedback winding right or it will not 
oscillate. Find the direction of the winding 
making up the original 9054 by looking for 
the wire coming off the outside and going to 
one of the two terminals. Then wind on an 
additional 6 turns in the same direction 
without changing LK Figure 4 should show 
you exactly how this is done. Join the start 
of L2 to the outer end of LI at the pin. This 
point will now become the emitter tap 
connection as shown in Fig. 3. Bring out the 
finish of L2 and connect it to the B+, 
bypassed by C3. 

Wind on one turn for L3 on top of LI 
and L2 (a little coil dope helps hold them 
on). I use coil wax for easy changing, due to 
my experimental work, but coil dope ce- 
ment is all right once the circuit is working 
correctly. 



+ 12 



01 



5K HEP53 



50-300 




U 

MILLER 
9054 



L2 
(SEE TEXT] 
FIG, 4 



L3 

itur^ to 

MIXER 



r 

HE 



lh 



L1 = Miller, 9054 

l_2 = Add-on winding, see text and 

Fig. 4. 
L3 = 1 turn. 

Fig, 3, Converter, local oscillator, 1,785 MHz. 

How to do it. Remove the aluminum can 
from the Miller 9054 coil by bending back 
the little tabs holding it in place, and make 



^r*s D.c. 




Fig. 5. Diode rf tester. 

And that's it, You can clip on an rf 
detector as shown in Fig, 5 for a check on 
power and frequency. Use an absorption 
wavemeter or a dipper in the diode position 
for this test to find the fundamental. Then 
you can trim up to an exact spot with your 
receiver. 



64 



73 MAGAZINE 







Sensibly priced for the maximum number of Hams. 




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LOAD 




WATTMETER 



only 
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and 1000 watts at 52 ohms, the Apollo is unique in that a solid dielectric heat sink is 
used instead of the pesty liquid variety. Moreover, the targe easy to read meter is zener 
protected in case you apply high power to a low power range. The load itself is rated 
350 watts in dry air, is made of non-inductive Carborundum and when packaged in the 
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Additionally, this device enables a direct percentage of modulation readout on the 10 
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One more fact the Apollo load is flat through 40 MHz and usable with ±10% 
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Use the least amount of power needed to 
drive the mixer. This will cut down on 1 .785 
MHz harmonics and "birdies" from getting 
into the front end of your complete receiver. 
The value of shielding cannot be overem- 
phasized. Keep any and all rf out of the 
battery leads, and keep closed-in cable con- 
nections to your beam antenna lead. 

The best things for elimination of birdies 
can thus be listed as follows: 

• Reduce oscillator power. 

• Carefully shield the oscillator and mixer, 
and filter the battery leads. 

• Shield the front end from nearby pick- 
up. 

Note that the birdies are 1,785 MHz 
harmonics and are not i-f leakage, which is 
pickup of signals on 1-65 MHz. I-f leakage is 
much more troublesome up front in a 
receiver, such as on 10 meters, between the 

28 MHz tuner and the VHF or UHF conver- 
ter. In times past I've been startled to hear a 
W9 calling CQ on 2m, only to find he was on 

29 MHz. Plenty of VHF converter output 
swamps such pickup, and good cabling and 
front-end shielding help to minimize that 
type of leakage. 

Do-It-Yourself-Filter 

As mentioned in the diode section (later) 
on demodulation, the more tests I make, the 
more I like the diode across the entire 
inductance; however, the selectivity suffers a 
little as a result. Looking for that some- 
times-elusive 3-4 kHz bandwidth f I decided 
to check the operation of a filter. I'm not 
always particularly impressed with the way 
some designers use filters. They have a 
tendency to use just one filter and a lot of 
amplification along with it; and it doesn't 
always sound right in operation. So this one 
was started with plenty of reservations; but 
after several days of trial and retrial it turned 
out to be a real goodie. That is, when used in 
conjunction with three other other tuned 
circuits as well as on 135 kHz, Figure 6 
shows the circuit which is a simple "top- 
coupled" two section job. There are several 
methods of coupling filter sections, such as 
link, mutual induction, and magnetic 
(wound on the same core but spaced). The 
one shown worked out best and is fairly easy 
to adjust, with one caution: With a given 



number of link-coupling turns, maximum 
transfer of energy may be 10 dB or so down, 
even with the best adjustment of C, It is a 



LI 4T 
ON 9060 



FROM 
IfiSMHi 
TO 135 KHz 
CONVERTER 



r 



3 



nh 



L2 



*£=*+ 



^MILLER 
9060 



IM 



if 



C2 




T0I39KH.Z 
l-F 



[QQ pf VARIABLE, 
HAMWARLUNO OR EQUiV 

L1 = 4 turns wound on 9060 

L2 = Miller 9060 

L3 = Miller 9060 

L4 = 4 turns wound on L3 

Fig, 6. i 35 kHz filter, 

combination of the proper number of link- 
coupling turns (LI and L4) that produce the 
happy result of low transfer loss and mini- 
mum usable bandwidth. 

Theoretical design of filters is a very 
complicated affair mathematically, with no 
place in this article. Just make it as shown in 
Fig. 6 and it will do fine. The entire i-f is 
already too sharp for a hi-fi AM tuner right 
now, and does cut the highs noticeably. You 
could add another filter with possibly an- 
other HEP 590 in between but then you 
might not be able to use it on AM voice. 

This filter, in combination with the three 
other tuned circuits, has been put to use 

here for several days, changing back and 
forth between 10 meters, the BC band, and 
the signal generator. This BC band can be 
quite informative when used with the signal 
generator and the amateur bands, because 
you do want to be able to understand the 
other party to a QSO even though you're 
looking for a lot of selectivity. When you 
have 8 to 10 kHz of flat-top bandwidth, you 
can do pretty well on the clear channel 
stations, This clear channel business con- 
cerns the FCC's frequency allocations and 
does not take into account the ideas of 
Canadians, Mexicans, and Cuban broad- 
casters, to mention a few. The best thing to 
do for this test is to check your location and 
the frequency allocations for a strong local 
and a not-too-distant next-channel station in 
the daytime. Incidentally, look out for those 
BC stations that use over 100% modulation. 
The most powerful one in Massachusetts 
does just that! 



66 



73 MAGAZINE 







When I check on the signal genera tor* 
using the filter, and measure ±1.5-2 kHz for 
about 6 dB down, Fve got a good communi- 
cations set bandwidth. This shows up on the 
BC band with definite cutting of highs. Bear 
in mind we are not talking about a $600 set, 
which can afford bandwidth switching. This 
is just a good homebrew filter job that can 
be put together on your bench for a few 
dollars, plus more than just a few days. 

For best results this unit should be 
installed in a Minibox, although it also 
handled well on a copper-clad 5 x 8 in. 
baseboard. You can also switch the filter in 
and out, with suitable care, as in Fig- 7. 




aJ^ 135 KHz l-F 



FROM I 65 MHz TO 
133 KHz CONVERTER 



Fig. 7. Bandwidth switch, 155 kHz filter, 



Demodulator 

I spent lots of time on the demodulator, 
most of it in conjunction with the band- 
width determination and the filter oper- 
ation, as these all go together to produce the 
desired results. The avc system is also tailor- 
ed to fit in with the demodulator. 

Believe it or not, those of you new 
readers who have yet to experience hours- 
long DX work on VHF or UHF ? the "rush- 
ing" sound of the noise made by the receiver 
itself can be important, It should not be a 
shrill hiss; it should be a "businesslike" roar, 
of low tone, and the slightest hint of a 
signal, even the smallest fraction of a micro- 
volt, should be detectable (by ear as well as 
on the S-meter). You can see the logic of 
this when you consider the bandwidth of 
noise itself. With this i-f system, demodu- 
lator, filter, and af, the above is what 
happens. Of course, you do need a low noise 
front end also and this need automatically 



becomes greater as you go from 6 to 2 
meters, and on up. 

Figure 8 shows the best circuit found for 
the important function of demodulation. 
With this one you will hear that signal, the af 




.01 



IN2S5 



AT Lf AST 
2 



PIN 6 




LARGE 
RFC 



01 



X 



-*TG AF 



I0K 



^ 



Fig. 8. Best demodulator circuit. 



quality will be good, and your chances of 
enjoying those QSOs will be best. 

It should be followed by a good tone 

control circuit and a good af amplifier such 
as the Amperex TAA-300, and a good 
speaker. You need some lows in there to 
punch through the QRNL 

AVC Circuit 

The use of the Motorola HEP 590 as an 
i-f amplifier results in considerable advan- 
tage, but it also changes the avc require- 
ments, as you will see. 

Referring to Fig. 9, pin 5 of the HEP 590 




POSITIVE VOLTAGE TO PIN 5. 590 

Fig. 9. AVC module. 

is the avc connection. When pin 5 has 6V or 
more of positive voltage, the current of Ql is 
shunted through Q3> and taken away from 
Q2 which reduces the gain of the entire 
circuit. The big advantage with the IC is that 
avc can be applied to the last i-f stage, which 
is also the same stage that is driving the avc 
system. With a single transistor amplifier 
stage, this is not normally recommended, 
but with the HEP 590 it works fine. Another 
advantage is that you now have places to 
install an S-meter that reads forward. This is 



MAY 1970 



67 




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across the avc amplifier collector resistor 
(Fig, 9). 

Figure 9 shows the final circuit which 
holds the rectified dc voltage down to less 
than IV— even on those Texas kilowatts, A 
PNP transistor is used in an "upside-down" 
fashion as the avc amplifier, An advantage of 
the use of an avc amplifier is that very little 
of the i-f energy is needed to operate the avc 
system, and no noise at all is contributed by 
it to the signals. 

When testing this out on a signal, with the 
ave module removed from the IC, the effect 

of connecting or disconnecting CI from the 
i-f was hardly noticeable* I may be a fanatic 
on conserving demodulator power and quali- 
ty, but it sure pays off when listening to 
those DX UHF stations! 

When testing this out on a signal, with the 
avc module removed from the IC, the effect 
of connecting or disconnecting CI from the 
i-f was hardly noticeable. I may be a fanatic 
on conserving demodulator power and 
quality but it sure pays off when listening to 
those DX UHF stations! 

How it works. Referring to Fig. 9 5 a small 
portion of the 135 kHz i-f energy is taken 
off the IC output inductor through the 
trimmer CI and fed to diode Dl. Capacitor 
CI is a very handy place to adjust the 
amount of avc action. With a meter checking 
the dc output of the demodulator, backing 
off on CI drops the avc output and raises 
the diode voltage to a point where D2 
overloads. Increasing CI raises the avc out- 
put and drops the voltage on D2 to less than 
IV on the loudest signals. You can set this 
to suit your own fancy. 

The i-f voltage on DI causes negative 
voltage to appear at the base of Ql (a PNP 
connected upside-down), which then con- 
ducts, driving the collector towards the 
+12V. This positive output is filtered by C3 
and applied to pin 5 of the IC amplifier 
where, as soon as the 6V level is reached, it 
begins to cut down on the gain of the HEP 
590, On a very strong signal, like a W5 on 
10m with an ordinary band opening, this 
voltage may reach plus VAV or so. It is 
perfectly possible to apply the avc voltage to 
the HEP 590 used in the 1.65 MHz i-f also, 
but this is taken up later, when the whole 



68 



73 MAGAZINE 



system gets packaged into its 99% "ideal" 
form, in Miniboxes, 

Don't be worried about the upside-down 
PNP, This is a usual practice nowadays. Just 
"stand" on the +12V bus as though it were 
the ground, along with the emitter, and look 
at the ground as though it were the battery 
voltage for the collector. It works! 

Complete System Tuneup and Operation 

This is where you can really take it on the 
chin as you first turn the entire rig on, with 
unbelievable sounds coming from the speak- 
er. Too much gain, birdies, low- frequency 
burble, high-frequency oscillations, broad- 
tuning squeals, and assorted tunable hisses 
are some of the things that can assault your 
ears when you connect an antenna, the 10 
meter front end> the first i-f, the second 
converter, the filter, the second i-f, demodu- 
lator, af, and speaker— and switch on the 
battery. (The overall circuit, incidentally, is 
shown in Fig. 10.) 



Table I. CoUs for "ideal" i-f system. 



L 

1 

2 

3 

4 

5 

6 

7 

3 

9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
RFC 



Number of turns 
or coil type 

1 turn 

M .'Her 9054 

4 turns 

9054 

3 turns 

3 turns 

9054 

3 turns 

15 turns 

Miller 9059 

3 turns 
9054 

6 turns 
1 turn 

4 turns 
Miller 9060 
Miller 9060 

4 turns 

5 turns 
9060 
10 turns 
9060 
Large 



Notes 

Wind on 9054 

Wind on 9054, L2 

Wind on 9054, L4 
Wind on L7 

Wind on L7 
Wind on L7 

Wind on L10 

Add on to L12 (text) 

Wind on L16 



Wind on L17 
Wind on L20 

Wind on L20 

Self-resonant below 
100 kHz 



I 785 MHi 
T0 0I 



BOTTOM OR 
LEAD, VIEW 



INPUT 
FROM 

TEN METER 
CONVERTER 



TUNE TO 

I65 MHz 







Fig. JO, Overall circuit, i-f system. 



AT LEAST 



In commercial receivers you often see items 
such as a 300£2 resistor in series with the 
mixer collector, going to the i-f output 
transformer, or a large bypass capacitor to 
ground on a mixer emitter which at the same 
time is supposed to receive oscillator inject- 



ion. It does apparently, but only in spite of 
all known electrical laws! Such fixes can be 
considered legitimate in that they do allow 
the system to operate in a satisfactory 
manner, but in my work I feel that the 
readers deserve to be told the truth -if it can 



MAY 1970 



69 



be found! It is not always easy to dig down 
to the basic troubles, though -especially in 
cases like birdies in the front end from a 
second local oscillator (or third, when triple 
conversion is used). It also takes space 
because when your breadboards are spread 
out over two benches (see block diagram, 
Fig. 1) your i-f, af, and speaker wires can 
sometimes radiate just enough spurious to 
get back into the antenna wires or front end, 
with high gain and loud signals— that is, if 
shielding, closed connectors, and coax cables 
are not used. A beam, or at the very least a 
coax-connected antenna outside the shack, is 
very useful. 

Mixers in particular are always suspect for 
my money. I have recently changed from my 
favorite mixer circuit over to one in which 
the mixer emitter is firmly tied down to the 
ground plane, rf-wise. This whole system 
performed in fine shape as soon as the 
mixers received the above-outlined treat- 
ment and avc was applied. The work on the 
demodulation proved especially valuable* 
allowing plenty of good i-f voltage to be 
handled by the diode. This in turn makes for 
good avc action, which has been detailed in 
the avc section. 

You can also see that packaging of each 
unit, removal of rf and i-f from the battery 
wires, and proper interconnections can be 
quite important. The use of a shielded cable 
going to at least a two-element beam outside 
the shack is recommended. 

You do want a powerful, selective, port- 
able receiver, don't you? One that can be 
used on 6 or 2 meters or the UHF bands? 
And in a nice little carrying rack with a 
companion transmitter? With quite a lot 
more work to come in the packaging bit, we 
hope to finally provide you with the plans 
for such an "ideal" rig, of reasonable size 
and cost, for use anywhere. 

Trouble Department 

You might think a mixer would be the 
last item in a receiver to develop real 
trouble, After all, it is supposed to just sit 
there, and is not supposed to oscillate or 
amplify, although some of them do have 
quite a lot of conversion gain. What would 
you say about one that oscillated about 5V 
worth all by itself?, , .cut off the local- 



oscillator drive, remove any input and still it 
oscillates? Well, it happened here and it 
could happen to you. So here I tell it like it 
is and 1 hope it will help you to avoid at 
least that trouble. It cost me days and a 
burned out HEP 590 too. 

Figure 1 1 shows the circuit that did it. 
DO NOT USE IT! It so happens that to 
make an oscillator* you ground the base, put 

a tuned circuit in the collector, and lift the 



BASE TIED 
DOWH TOO 
CLOSELY 
TO GROUND 



MIXER 




r 



*I2V 



X 



C 



FROM OSC 



EMITTER NOT 
SUFFICIENTLY 
BYPASSED 



Fig. 12. Trouble-prone mixer circuit. (Do not u$e T ) 

emitter off ground. See the resemblance? In 
that mixer the emitter can be considered to 
be grounded through C2, but it is not a 
positive ground. Also, the base is not sup- 
posed to be grounded, but there is a very 
short low-impedance path through CI and 
LI, or the base input tap on the rf collector 
coil. Well, to cut the sad story short, it did 
oscillate, , .like mad! So the circuit shown in 
the mixer section, Fig. 2, was installed and 
so far this mixer has not oscillated since 
then. Period, 

Results 

The finished system was hooked up as 
shown in the block diagram, Fig. 1 , with my 
faithful old 100 ft wire attached to the 10 
meter front end. Being early in the morning, 
the first station on the dial was a ZS in 
South Africa, pushing the S-meter around in 
lively fashion, soon followed by lots of 
others over there. A little later W5s came 
booming in to provide checks on the avc 
section with extra-loud signals. Some of 
these latter produced nearly 10V of de- 
modulator diode output with the avc off. 
This overloads it, of course, and it is not 
used in this condition. With the avc con- 
nected it held nicely to 1 V or lower, 
adjustable by the 5-8 pF avc coupling 
capacitor. Manual control is applied to pin 5 
of the 1.65 MHz IC amplifier, as indicated in 



70 



73 MAGAZINE 






fO* 



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73 Magazine 

Peterborough, N. H. 03458 









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the first part of this article, to regulate the 
overall sensitivity and the amount of receiver 
noise. The results of using an excellent 
demodulator, the Amperex TAA-300 "baby 
hi-fi" amplifier, and a good speaker now- 
showed up in a pleasing fashion. Advancing 
the af gain as for use in mobile work or in a 
large noisy room, etc. did not result in tinny 
audio or distortion, but produced good 
quality audio which was a pleasure to the 
ears. 

The avc swallowed up 90$ of the QSB, 
even 100'' of everything that could reason- 
ably be called Q5. As mentioned in the avc 
section, the small trimmer coupling capaci- 
tor bringing i-f energy over to the avc 
module provides excellent adjustable regula- 
tion of the amount of avc you may prefer. 

The use of a good dial in the tunable i-f 
on 10 meters is imperative for an i-f of this 
bandwidth. The Miller MD-4 two-speed dial 
does a good job in that unit. 

If you want to "steal a march 1 ' on my 
work here, install a bandwidth switch in 
front of the filter to cut it in or out. Figure 
7 shows this unit, but mind you, I haven't 
installed it yet, so you Ye on your own. I 
have plugged and unplugged the filler 
though, many times, so I know whal will 
happen if you beat me to it. There is an 
increase in bandwidth when vou cut I lie 
filter out. This is good for non-DX com acts 
and locals. For real DX, switch to the 3-4 
kHz bandwidth position, which cuts it down 
to the minimum noise condition. 

Conclusion 

Design methods, breadboard circuits, 
overall tests, and results have been detailed 
for you, trending well on the way towards 
an "ideal 1 * battery-operated i-f system with 
low image and high selectivity, which, when 
packaged, will be a very useful piece of 
equipment for the active \ HF UHF ama- 
teur. 

This will soon be matched up with the 
packaged, single-dial, three-gang tuned 10 
meter i-f for use with any VHF-UHF 
converter, homebrew or store-bought. You 
will then have an excellent, portable, solid- 
state receiver thai cannot be bought ready- 
made on the market today. 

. . .K1CLL" 



72 



73 MAGAZINE 












Elliots. Kanter W9KXJ 
3242 W. Hollywood Ave. 
Chicago IL 60645 



With the wealth of new materials and 
devices available to the ham today, 
ii seems a shame to keep on building with 
worn out and antiquated methods. I am 
speaking of soldering, a process that has 
changed little since the days of heating a 
soldering iron over an open flame and then 
melting wire solder. This progressed to 
electrically heated irons or guns, but the 
basic principle remained the same: heat the 
solder and the terminal. 

Until recently this was about all we 
could use and we tried to make the best of 
it. Heatsinks had to be used to protect our 
semiconductors, and of course, we had to 
be sure we didn't overheat the PC board 
and lift a conductor. 

Well, there is a way to get around the 
problems of cold solder joints and heat- 
damaged components: epoxvl Not the 
usual form of epoxy* mind you, but an 
altogether different form— one which is 
electrically conductive, that can be cured 
at room temperature. [ dashed off a line to 
Emerson & Cuming in Canton, Mass., and 
received a wealth of information on the 
world of epoxies. I learned that there are 
epoxies which are thermally conductive, 
yet still electrical insulators, and that a 
product called Eccobond Solder 72C was 
the IC manufacturer's answer to the solder 
of yesterday. 

I sent away for some of this ^solder' 
and followed the simple mixing instruc- 
tions, A test circuit was put together using 
the liquid solder as a conductor between a 
battery and a small lamp. It worked like a 
copper wire, and during the cure period 



could be moved or removed with ease. 
Ohmmeter checks showed that it has low 
resistance and remains stable regardless of 
the applied voltage. 

Next, I tried to solder dissimilar metals 
together (a copper wire to an aluminum 
chassis) and found it would not only 
provide a solid electrical bond, but had 
good mechanical properties as well. A 
friend borrowed some and proceeded to 
wire his new transceiver using the epoxy 
solder in place of regular solder, His report: 
no cold solder joints, no heatsinks needed, 
and -best of all— no heat-damaged GOBI* 
ponents. 

The epoxy solder in one form or 
another has found acceptance with many 
manufacturers of electronic equipment 
since it allows good reliable connections by 
unskilled personnel and in many cases does 
away with heatsinks. 

Looking further into the catalog and 
spec sheets. I discovered thermally conduc- 
tive epoxies which allow you to use the 
chassis as a heatsink. All you have to do is 
squirt a glob on the chassis and press the 
transistor into it. The epoxy presents a 
thermally conductive bond which is still an 
electrically isolated one. 

All of the various forms of epoxies are 
available from the major electronics distri- 
butors and may be found in their industrial 
catalog section. Say goodbye to burned 
fingers and soldering irons and move up to 
conductive epoxies. The component 
packaging specialists did it a long time ago. 

. . . W9KXJ ■ 






MAY 1970 



73 






Many amateurs come to the point 
where they need an extra pre- 
amplifier for wider coverage with their 
mobile FM operation, I have constructed 
several field effect transistor amplifiers for 
6 and 2 meters which yielded many inter- 
esting results. Approximately twice as 
much gain may be achieved when using a 
field effect transistor in the grounded- 
source arrangement as compared with the 
grounded-gate configuration for the same 
bandwidth; however, neutralization is al- 
most always required. By using a field 
effect transistor in the grounded-gate con- 
figuration, the amplifier was simple to 
build, gave adequate gain and bandwidth 
with a low noise figure and ease of tuning. 
The low feedthrough capacitance elimina- 



FET 

Preamplifiers 

FOR VHF 
FM 



Earnest A. Franke VJA4WDK/2 
108 Maiawan Terrace 
Matawan N J 07747 



LI.L2-2M 8 TURNS JGAWG 6M ii TUftNS 28AWG 

CJ.C2-2M Spf 6M 20 pF E F JOHNSON VAH I ABL£S 

•6rt-0HMlTE Z-5Q 
2m*QHMlTE Z-M*4 



—VERTICAL SHIELDS 



9 



0^ 





1*100 




fh 



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->b, ! 

I 

/h o 



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I tooo ' j .( 



fft 



ioooi 






' 




STANDOFF -* 



T 01 



*t2V. lOmA 



IN 



2N3623 TJS34 



Fig. L Cascade preamp circuit, using two 
grounded-gate FETs, provides plenty of rf gain 
on 6 or 2 meters. Frequency-sensitive values are 
listed at the upper left portion of the diagram. 



A grounded-gate FET preamplifier 
for 6 or 2 meters offers high gain, 

simplicity of construction 
and ease of tuning. 



ted any need for neutralization. The only 
tuning after construction is to peak the 
two tank circuits for resonance. When the 
preamp is used in mobile operation^ the 
supply voltage may be taken from the car 
battery. 

The schematic of Fig. 1 shows the 
2N3823 (or TIS 34) field effect transistor 
cascaded in the common-gate configura- 
tion. An inpul tank circuit was tried and 
replaced by a simple rf choke to provide 
the rf input load. The low input impedance 



74 



73 MAGAZINE 



into a grounded-gate configuration tends to 
broaden or swamp any input tank circuit. 
The biasing resistor is bypassed to provide 
the rf ground. Two INI 00 diodes were 
placed back-to-back at the input connector 
to prevent possible overload damage, Poor 
isolation, especially in the antenna relay, 
could easily destroy the input transistor. 

Construction 

The amplifier was mounted on a piece 
of copper-clad printed circuit board- The 
board, with the copper on but one side, is 
cut to length and drilled as shown in Fig. 2. 
The general layout may be increased if 
parts appear too cramped- Notches must be 
cut in the vertical shields for the transistor 
sockets, The boards and component leads 



spread to 3 A in- long and tapped 2 turns 
from the supply voltage end- Each 6 meter 
coil is wound on a 3/8 in. diameter rod 
using 13 turns of 28 AWG wire, tightly 
spaced and tapped 7 l A turns from the 
cold end. Care must be taken when solder- 
ing the leads to the Johnson capacitors. 
The stator plates are held in position by 
solder during manufacture and may fall 
apart when heated* Maximum capacitance 
values of 5 pF for 2 meters and 20 pF lor 6 
meters were chosen for the variables so 
that they would be in their mid-position at 
resonance. The output tap may be varied 
to determine bandwidth and gain. The 
positions shown here are not critical, but 
are a compromise for broad bandwidth, 
A CU-2 1 01 A Minibox is drilled to allow 



2 N 302 3 SOCKETS SHOW* HERE 



4 m ~^H> 



3^rn 



jtr\ *j* 



•i 1 " — h 



PC BOARD VERTICAL SHIELDS 
I | 3/4 in X 1 1/4 in ) 




Fig, 2, Sketch shows layout of FET preamp, 
Note use of shield walls between stages. 



21 -- 
19- 
17- 
£ 15 






id 



9 



▼ ^T 



I46 94MH* 




\44 J46 |4fl I5€ 
FREQUENCY [MH*] 



52 525 MHz 



* 



f- 






+ 



50 51 52 53 54 

FREQUENCY (MHa) 



55 



Fig, 3, Gain-hand width curves for 2 and 6 meter 
versions of the FET preamps. Note that gain 
peaks at about 20 dB in both instances. 



are then cleaned with steel wool to prepare 
a good soldering surface. After the sockets 
are mounted, the vertical shields are sol- 
dered in place neatly and evenly using a 
small soldering iron. The standoff button 
bypass capacitors are soldered firmly to the 
board. All ground connections are made by 
directly soldering the part down on the 
copper, 

The 2 meter coils are wound on a % 
in. diameter rocf using 8 turns of 16 AWG 
enamel-coated copper wire. The coils are 



passage of the connectors, sockets, and 
capacitor shafts. The printed circuit board 
chassis is then bolted to the Minibox top 
and labeled with dry transfers or decals. 

Performance 

With a 12V supply, the preamp draws 
about 10 mA total current. The two 
capacitors are tuned to resonance simply 
by peaking on noise. Figure 3 shows the 
response characteristics of each preamp. 
From the results shown, the 2 meter 



MAY 1970 



75 



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76 



73 MAGAZINE 








THE 



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'R" — Close dot dash key. During the dash or second dot release dash-dot key, 
'P" — Close dot-dash key. During the second dash or dot, release dash-dot key, 
'L pr — Close dot key. During the first dot, flick the dash key. Release dot key during the last dot. 
"B" — Close dash-dot key. Release dash key at any time during the 
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"Double Dash" — close dash-dot key. Release dot dash key during 
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the amplifier has at least 16 dB gain over^ 
the entire 2 meter band when peaked near 
146 MHz. The 3 dB bandwidth of the 6 
meter amplifier is only 2 MHz. When 
peaked at 52.525 MHz, the amplifier will 
have greater than 20 dB, The addition of 
either preamplifier should help to solve 
many of the sensitivity problems, especi- 
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. , . WA4WDK/2 



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MAY 1970 



77 





The warning or "idiot" lights provided 
as replacements for dashboard meters 

in most modern automobiles leave a lot to 
be desired. Two of their more obvious 
shortcomings are: (1) they may be illumi- 
nated for some time before being noticed, 
especially on a bright sunny day; or (2) 
they may burn out without warning, 
leaving the driver with no warning at all- 
Taking a leaf out of the aircraft 
designers handbook, what is needed is a 
method of drawing the driver's,attention to 
the lamps as soon as they light, as the 
malfunction may be serious enough to 
require immediate attention. The device to 
be described will cause the illumination of 
any idiot light to sound an audible alarm. 
The" immediate disadvantage to such a 
system is that if the light remains on for 
some time (as, for example, if you have to 
drive some distance to a service station), 
the continuous sounding of the alarm 
could become dangerously distracting- To 
prevent this, an "override** switch has been 
incorporated to disable the alarm once it 
has served its purpose. However the circuit 
incorporates an automatic reset feature 
which will reset the alarm once the fault is 
corrected, so that the next time an idiot 
light comes on it will sound again without 
the need for any action on the part of the 
driver. An added feature of this circuit is 
that if the fault is not corrected, the alarm 
will come on next time the car is started: 
also, each time the car is started, the alarm 
will sound for a moment as an automatic 
test of its readiness. 



The alarm itself (see Fig. 1) consists of a 
12V buzzer, and the reset circuit is com- 
posed of a small spdt relay and 
a momentary -contact spst pushbutton 
switch. The alarm is connected to the idiot 
lights through a number of diodes which 
serve to allow the different light circuits to 
trigger a single alarm without shorting all 
the lights together. 



1 DISABLE 
SWITCH 



GEN 



OtL <* 



TEMP * 




«J t 




DIODES ARE 
20PIV, IOA 



LEV 
8UZZER 



J 



TO ADDETJONAL 
CIRCUITS 



Fig. 1: Circuit diagram of audible "idiot light 11 
alarm. 



When one of the idiot lights comes on. 
the voltage is passed through the appro- 
priate diode, through the relay contacts, 
and on to the alarm buzzer, When the 
driver wishes to silence the alarm he pushes 
the switch; this shorts the normally open 
relay contacts, and results in the current 
being diverted from the buzzer to the relay 
coil- The relay is now energized and holds 
the contacts closed, leaving the buzzer 
disconnected. When the fault is repaired 
and the light goes out, the relay is no 
longer energized and returns to its normal 



78 



73 MAGAZINE 



D. J. Holford 
RR 1, Enfield 
Hants County 
Nova Scotia, Canada 





position, resulting in the buzzer again being 
connected to the input ready to sound off 
next time a light is illuminated. 

The alarm is not restricted to just those 
functions provided by the idiot lights, and 
can warn of any situation capable of being 
indicated by an electrical signal. For 
example, it could be used to warn of lights 
being left on when the ignition is off by 
use of a suitable circuit. 



i 



DASH 



WARNING 

LIGHTS 



V 




DISABLE 



Fig, 2. Suggested mounting method and panel 
layout. 

The diodes and buzzer can be concealed 
out of sight under the dash (Fig. 2), and 
the only item which needs to be exposed 
to view is the pushbutton disable switch; 
however, I prefer to have an integrated 
warning panel which saves having to look 
around to see which light is lit. 1 duplicated 
all the normal warning lights, plus others 
for the additional circuits which can trigger 
the alarm, and installed them all in a small 
master warning panel together with the 
disable switch. 

There are a number of suitable locations 
for such a panel. The easiest and most 
obvious is under the dash, but items under 
the dash have a habit of getting in the way 
of knees, I preferred to make a small panel 
and install it in the center of the roof 
above the rear-view mirror, where all I have 



to do is glance up to see what happened. 
Another good place for those who have 
given up smoking is to make a small box 
which will fit in the ashtray space, and 
paint it to match the dash. Since there are 
very few parts, and they can all be minia- 
ture, it does not require much space. 

I have not included detailed layout and 
construction plans as the design can be 
easily customized to your own car and 
personal desires. The circuits will all be 
basically the same, but the placement of 
components will vary. Also some may want 
duplicated lights and a custom warning 
panel, while others will conceal the buzzer 
under the dash, and only the switch will 
show. 

Any small 12V spdt relay will do, plus 
a 12V buzzer, a pushbutton switch, and 
the required number of diodes. The diodes 
are not critical as long as they can handle 
about 1A at 15— 20V. There are a multi- 
tude of diodes and relays available at low 

prices so the constructor should have no 
problem obtaining parts. 

Construction and installation can be 
easily accomplished in one evening, and the 
result is an impressive and effective addi- 
tion to any automobile. 

If you decide to add the duplicate 
lights, you can obtain small self-contained 
12V pilot lights at the local radio store for 
a small sum. One final point to remem- 
ber: The diodes must be insulated from 
ground, as both sides are carrying 12V. 

. . . D. J. Holford ■ 



MAY 1970 



79 



N-J 



o 



o 



CO 



o 



PQ 





TRANSMITTER 





//onMf //7/«/7 - . . you can build one in your cigarette lighter! 



You can really hide this one, even in 
the skin of a bear! It's only % x % x 

I /X in,, is crystal controlled, puis out li i> lo 
Va wliM. on meters, and can he used for 
biological work, survival units, etc. With a 
6 in. antenna I've heard it out to 15 mile 

I his article describes what can be done 
on VHI-" today with off-the-shelf submini- 
ature items. Of course you do have to look 
hard tor some of those shelves - but they 
arc available 



The Crys 

Vs far as I know McCoy is the sole 
manufacturer of a suitable crystal less than 
8 in. thick. McCoy lias a special glass 
blower (from the Old Country?) who 
encloses the liny little crystals in glass. 
These gems work, and work extremely 
well I've even run 15 mW through the 
crystal itself and so far no trouble. 

figure 1 shows a sketch with dimen- 
sions of this jewel in its Type MM glass 
package. Of course they don't just give 
them away, but where else can you get one 



I 10 mils thick? There is still the next size 
up, the M-0. with a "Tin can" holder which 
is 183 mils thick, if you have the room. 

1 recently acquired two of the MM units 
and they both worked immediately in the 
circuit shown in Hg. 2 and have continued 
to work ever ;nee; so they arenT iusf 
pieces of costume jewelry. 



28'* 



f£.ff- - * 



v 



Q2 ' / <^"> Ya 



" * / / J ' " 



*i«TE LEADS 



" 







Fig. I. McCoy's Type MM crystal is an incredibly 
small element enclosed in a tiny glass package not 
much larger than a thick-film capacitor chip. Less 
that U8 in. thick, the area of the crystal is about 
in* square 



80 



73 MAGAZINE 



C3 \iX JL LOW 



5~BOpF j| 

** Tf IMPEDANCE (50 
^ OHMS) TEST JACK 




10V 



NOTES: 

1. "Ground" is the copperclad 
baseboard plus the battery, 

2. J1 should light a No. 48 or 
49 pilot Mght bright. 

3. L2 will vary with antenna 
size. 

4. Check final tuning carefully 
with CIA and C(B compared 
to a No. 463 Arco mica trin> 
mer\ 10 to 180 pF, 



Fig, 2, Even though the transmitter packs down in density to about the size of a postage stamp, the 
circuit is straightforward and without surprises For the builder. 



Transistor 

Just for fun you might say, I soon tried 
the Motorola HEP 55 , but after checking 
against others ol' the same size of smaller, I 
stayed with it. After all, it's only SI. 20, it 
is plastic, and can easily be filed down to 



the desired 1/8 in. thickness. The plastic 
takes up about a third of the overall 
thickness of these little powerhouses, so 
you can easily file down to J 25, a little on 
each side, I also checked out several dozen 
of them for "activity" in the circuit of Fig. X 













NOTES: 

C1 and C2: 100 pF small vari- 
able Hammarlund MAPCB, or 
similar. Calibrate knobs in pF 
for substitution by fixed capa- 
citors later. 



RED 



BLACK 




l-7pF 



l 0a HEP 55 



10V 




\£+ HI z 



OUT 



COPPERCLAD 




Fig. 3. Breadboarding the transmitter into a test configuration with regular-size component will give 
you the chance to get the "feel" of the circuit and its capabilities. 



MAY 1970 



81 



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by grading them as very good, good, and 
fair, I got about 10 in the very good 
category. The rest go fine in i-f circuits, so 
that settled that question. 

1 have run 45 mA at I0V for hours at a 
time, getting over 200 mW output of rf 
with no trouble of any kind; so there's no 
need to fear pushing a little if you have a 
few extra on hand. 

Coils 

There are two coils, one of which is for 
loading the 6 in, antenna, Made by 
Piconics, a suburban Boston company, the 
coils are tunable and tiny (less than 1/8 in. 
thick). The tunable feature is one of the 
major advantages of these coils because, as 
far as I know, there are no variable 
capacitors in existence less than 1/8 in. 
thick. 

Just to see what effect the tiny coil size 
had on the power output, I cut it down 
and kept cutting down until 1 reached the 
size of a piece of spaghetti about 80 mils 
diameter, wound with 34-gage wire. Even 
though I squashed it almost flat, the 
output power remained the same. When 



the circuit is properly tuned and loaded the 
coil really doesn't make much difference. 
Once again, the influence of the matched 
circuit and the loaded Q! If the proper 
amount and phase of feedback is there, 
which it is in this case, the rf output almost 
burns out a No. 48 bulb. 

The circuit tunes broad but correctly 
and smoothly, and stays exactly on 50 
MHz, or 50.4, or on whatever frequency 
the crystal is ground for. It also stays on 
the air, which is very important. As usual 
with any crystal oscillator, load it up to 
where it does go off the air, and then 
unload it so that it stays on the air with 
whatever battery voltage you may choose 
to use as the end of the battery life. 

Breadboard Test 

Use the test jig of Fig. 3 with large 
variable capacitors for tuning up and 
checking out the subminiature components 
before you mount and solder them into the 
tiny "chassis." I found that 15 turns of 
wire (32 or 34 AWG) with the crystal 
feedback tapped on at 5 turns from the 
low end was very good. Ten turns of 26 



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82 



73 MAGAZINE 



AWG on a threaded paper form was handy 
to start with, and sure-fire for use on 6 
meters. 

If you calibrate the knobs on the 
variable capacitors you can then substitute 
fixed values later when you get down to 
the subminiature size, and do the tuning 

r 

with the Piconics coil. This tiny wonder, 
shown in Fig. 4, actually has a core which 
moves in and out by means of threads in its 
nylon holder. Don't forget, you've got to 
tune something. It is possible to substitute 
fixed values of capacitors and make it 
work, but Pm assuming youVe handled 
enough transmitters to know the value of 
tuning up. A good Piconics coil for 6 
meters is the one labeled B121K713YL 
That's quite a mouthful, but it not only 
indicates the inductance but the ratio of 
the tap position as weil —just be happy 




Q90 tn.- 




B I/20W .090 in. 
RESISTOR J/ 



9/32 in. 
A. TUNABLE COIL 



< 




-070 



C. TERMINAL STRIP 



Fig. 4. Layouts and dimension of some of the 
"micro* * components in the postage stamp trans- 
mitter. 



that someone makes one that's on the shelf 
ready for you. 

Resistors 

Sprague Electric, Nashua, NT!,, makes 
good 1/20 watt resistors. They are precise 
and tiny, and they work. Figure 4 shows 
dimensions, *Nuff sed. 

Capacitors. 

Republic Electric makes capacitors up 
to the .01 fiF value used here* They have a 
maximum diameter of 60 mils. That's 
under 1/16 in., in case you haven't been in 
a machine shop lately. Every one of these 
skinny cylinders has worked properly. I 
don't know how they do it but I'm going 



to find out soon with a visit down into the 
wilds of Patterson, NJ. to see for myself. 

Mounting Strips 

I really had to turn on the old imagina- 
tion for this one. Past readers may recall 
my frequent use of ,021 "common pins/' 



SOLDER 



STRIP 



SOLDER 




003 to FIBER GLASS 



032 in. 
COPPERCLAD 



Fig. 5. Side view shows terminal strip utiiization 
and mounting technique. 



brass, nickel plated, for terminal strips, 
hammering them into 20-miI holes in fiber 
glass strips or linen-base Bakelite. Well, 
these are too big for this job! So I cut up 
some of the linen-base Bakelite stuff into 
square cross-section rods and drilled 
through the sides of them, as in Fig. 4C. 

Figure 5 shows the drilled strips, or 
"logs," with a small strip of ll^-or 3-mil 
fiber glass under it for security against ends 
of components or wires shorting to the 
base plate, and examples of components 
used. You can drill as many holes as you 
have wires or solder two or more wires 
together on one side of the strip. 

Chassis 

Figure 6 shows the baseboard cut out to 
receive the major components, which are 
the coil, the crystal, and the transistor. As 
these units are over 100 mils thick they 
cannot be mounted on top of the base- 
board but do very well in the cutouts with 
coil cement or other types of embedment 
added later. Although I am showing one 
example of a circuit with the 1/8 in. thick 
technique, you can of course use the same 
method for other circuits. I have gone up 
to 432 MHz with this type of construction, 
so various things can be done at the 1/8 in. 
thickness. After mounting and soldering, 
you can also use high-temperature coil wax 
for a test unit which you might want to 
change later. This can also be used for a 
"next to final" model. 

Batteries 

In my quest for a really tiny battery (1/8 
in. thick), I found that only two qualified 








MAY 1970 



83 



. 



MMH 



+ 10V - 



TUNE 



BLACK 



ANT 



SOLDER 




3/4 in. 



Fig, 6, Blowup top view shows layout of subminiature oscillator. Actual physical size of unit will be 
3/4 in. square. 



**. 



as ^desirables," and one of these was 
ultimately eliminated by testing. The two 
candidates were the silver oxide and the 
mercury types. The dimensions of the 
smallest is shown in Fig. 7. For up to about 
100 mW output, with a battery drain of 
about 20 mA at 10 V, a check was made on 
the above types. The silver oxide battery 
lasted 30 minutes and the mercury battery 
65 minutes. Of course, these tiny power 
sources are not, absolutely not, sold for 
any such use. In fact, the engineering 
department heads of the two largest bat- 
tery companies tend to either raise their 
voices or hang up the phone, or both, when 
they find out what you really want out of 
their little aspirin pill batteries. 

There are two immediate solutions: 
reduce power, or reduce the time on the 
air. For some uses — such as continuous 
monitoring with voice or other sound 
modulation — you have to reduce power 



for any reasonable life at all. This can be 
done very simply by using less battery 
voltage or increasing the resistance of the 
emitter resistor, or both, and a slight 
amount of retuning. For some other types 
of uses, such as biological tracking, hidden 
transmitter hunts, etc., you can turn the rig 
on for short periods only; for example, 10 
msec out of every second for an increase in 
battery life of better than 100 times. 
(There is nothing worse for battery ' life 
than a constant heavy drain,) This type of 
automatic keying is, as usual, another 
story. The tiniest little transistors, the 
Microtabs by GE, can be used for this 
service in a multivibrator circuit to drive 
another one of them in a simple on— off 
switch type of hookup. 

For the battery pack, a 1/16 in, sheet of 
soft plastic such as PVC (polyvinyl- 
chJoride) can be used to hold the batteries 
in a pack of four, six, or eight (or even ten 



84 



73 MAGAZINE 




if you like "high power") as shown in Fig. 
7. If you order a large quantity, Mallory 
will weld tabs on each pill-size battery and 
you can then solder them together to make 
up a pack. Count on no more than I.OV 
per cell, regardless of the drain you may 
expect, because they will soon enough 
reach this level, or even lower, unless you 
operate in a pulse mode. 




i 



n 



125m 



220m 



SOOm 




Fig. 7, The tiny battery can be used with other 
batteries if a holder is constructed from PVC as 
shown here. (Holder shown accommodates eight 
batteries.) 



For test operations I did solder leads 
onto them, much against the advice of the 
engineering departments of the battery 
companies. So far, no ill effects, but you 
have to do this very carefully. I used a 25 W 
iron well cleaned and tinned, shined up the 
battery case first, and then tinned it. A 
touch of perhaps less than one second does 
the trick, also using very-small-diameter 
solder. I am not advising this method, just 
mentioning that I did use it! Also, use 
flexible subminiature wire such as multiple 
strands of 34 AWG, for example, with 
Teflon insulation. These batteries can be 
purchased where hearing aids are sold and 
in many radio stores. Naturally, use the 
largest size you can put into your project. 
The "aspirin" size will only give a life of 1 2 
mA-hr at something like a 1 mA drain — 
not enough to operate the oscillator. It 
will run at around 4 mA, though. This 
power level is easily adjustable by the 
emitter resistor, as mentioned before. You 
can generally expect about 50% efficiency 
for dc input to rf output power with the 
circuit shown in Fig, 2. 

Circuit 

When I first made up this design I was 
looking for a foolproof crystal circuit, one 
that would not take off on any frequency 



other than the one marked on the case. 
The circuit shown achieves this goal; after 
working with it some time, I find that it 
can be a very powerful oscillator as well — 
stable and reliable. In a later 73 article 
(Solid-State Power on Six) you will see it 
running at over a watt, with up to 500 mW 
output! 

How it works 

Referring to Figs, 2 and 3, when the 
collector is tuned to 50.4 MHz, for exam- 
ple, by CI and LI, with 10V in, a volt or 
so on the base, a bypassed resistor from the 
emitter to ground, and a 50.4 MHz crystal 
connected between the base and the tap on 
LI, it will oscillate. It's a law of nature! 
Note that the feedback looks as though it 
was degenerative, or negative. It only looks 
that way though, because the crystal 
reverses the phase of the feedback voltage 
going to the base. This is a fact of life very 
difficult for some engineers to swallow but 
it works! Even the Curies in France in the 
last century knew that much about peizo- 
electric crystals. 

The result is advantageous. With positive 
feedback coupling, the oscillator can be 
quite critical for the right amount of 
feedback, tuning, and loading. With nega- 
tive feedback coupling, it will only oscillate 
when the crystal reverses the phase, which 
of course occurs only on its proper and 
marked frequency. Just how many half- 
waves of sound are standing across the 
crystal is the concern of the manufacturer, 
as long as these sound waves inside produce 
50 MHz electromagnetic waves on the 
outside, and vice versa of course- 
Crystal Power 

I think this is a matter to be decided by 
usage because, while the makers talk about 
2 or 3 mW of power in the crystal circuit, I 
found that a small pilot bulb in series with 
a 50 MHz crystal lights up a little on the 
1W oscillator. In the CW mode you will not 
run that much, but with pulsing you may 
well go over it. About 10 to 12 mW is 
required in the transistor base— crystal cir- 
cuit for about 500 mW out at the collector 
circuit. You can see that the gain of the 
transistor is important also. 






MAY 1970 



85 



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In the "Good Old Days," a pilot light 
was regularly installed in series with the 
crystal. Granted, those were big fat 
crystals, on 160 meters, etc., while we're 
talking here about a real skinny one, for 50 
MHz. After all, a wave, even if it's a 
slowpoke one like a sound wave, doesn't go 
very far if it has to stop after one fifty- 
millionth of a second. So you can take 
your choice as to the power you run. You 
can see that the more lively the transistor, 
the more power you can run from an 
oscillator with a given crystal's rf millh 
wattage. 

Antenna 

The tiny 6 in. antenna's performance 
was a surprise to me even after half a 
century in radio. Using the antenna and 
loading circuit shown in Fig, 8, I left the 
rig in a house in Jaffrey, N.H. and could 
still hear it in Francestown, more than 1 5 
miles away. On 6 meters, this is an antenna 
of about 1/36 wavelength long. You can be 
surprised or not, as you please. I was. The 



LARGE 
LOADING COIL 



v -.- 




Fig. S. Although several antennas and loading 

techniques were tested, the approach shown here 
proved significantly superior. 



only disadvantage of the antenna loading 
technique shown is that you need close to 
the right number of turns on L2; other 
loading techniques may be less critical, but 
experiments have shown that they are not 
as efficient when it comes to rf radiation. 

Receiver 1 

First, you need a diode field strength 
meter for use at a fixed distance, say a foot 
or so to start with, in order to tune up and 
compare radiated power. I soon found that 
the best setup was another short antenna 
clipped onto the diode detector's tuned 
circuit about halfway up the coil (Fig.9). 
For meter indication at maximum distance, 
the length of the whip and its contact 
position along LI are important. 



86 



73 MAGAZINE 







OGNO 



IN295.TAPPED ON AT 4 TURNS 

8TURNS,AIRW0UND,I0PER INCH 
2 TURNS AROUND LI, VARIABLE 
COUPLING 









Fig. 9. A diode detector makes a convenient and useful receiver for checking the performance of your 
postage-stamp transmitter while it's on the bench. 






Figure 9 shows the circuit I used, which 
is also a good frequency meter for checking 
to see if you are on 50 MHz and not on 
some harmonic. Never rely on a high-gain 
receiver for this basic fact. Use it to check 
for noise, hum, stability, etc. once the 
frequency has been determined, 

Polarization can also be checked with 
the diode receiver by using a regular 50 
MHz dipole (or beam if you can handle it 
physically) across the room, or outdoors if 
needed, with its matched cable plugged 
into Jl (Fig. 9h 

Receiver 2 

I put some tone modulation on the rig 
to identify it because at a distance of 15 
miles I .wanted to be sure; but of course 

you can use plain CW with a bfo it" you 
like. Either way, the signal comes in great 
with a regular receiver and beam on 6 
meters. 

For a particular purpose in mind I did 
build up a good hand-carried receiver for 



use with these little rigs, This is a semi- 
fixed-tuned job with small knobs on the 
tuning capacitors for test purposes - it 
tunes over the band in great style. The 
front end has a 1.7 dB noise figure, which 
is very useful because you can take it to 
absolute "hermit" locations, where such 
performance really counts . But, of course, 
that is a completely different story, and 
will be published later. 

List of Component Manufacturers 

Transistor: Motorola HEP 55 

Coil: Pi conies, Tyngsboro, Mass. 

Crystal: McCoy Electronics, Mt. Holly 

Springs, Pa. 
Capacitors: Republic Electronics Corp, 176 

E, 7th St., Patterson, NJ. 
Resistors: Sprague Electric, Nashua, N. H. 
Insulation: Insulating Fabricators, Inc. 

Watertown, Mass. 

. . . K1CLL" 



MAY 1970 



87 



Getting Your Extra 

Class License 



STAFF 



Part XVI : RF Power Amplifiers 



In the previous installment of this Extra 

Class study course, we began a discussion of 
some points of transmitter operation 

included on the official FCC study list of 
questions. This time, we'll conclude our look 
at the subject of transmitter operation. 

In the process, we'll examine the follow- 
ing FCC questions: 

40. How can the output circuit of a 
transmitter be adjusted to increase or 
decrease its coupling to the antenna system? 

50. What would happen if the grid-bias 
supply of a Class C modulated amplifier was 
suddenly short-circuited? 

61, What are some causes of the excessive 
production of harmonics in if amplifiers? 
How can these causes be remedied? 

62. What effect does a transmission line 
which is not properly terminated have on 
the plate tank circuit of a transmitter? 

78. Give some proven methods of har- 
monic reduction in transmitters. 

We'll follow our usual practice, and rather 
than providing specific answers to these 
specific questions, rephrase the questions 
into new queries with broader scope so that 



the general principles underlying the details 

can be brought out. 

These five questions group into three 
broad subjects-harmonics, antenna circuit 
interaction with the transmitter, and effect 
of losing grid bias. 

And as it happens, all three subjects are 
parts of the general subject "What Goes On 
In The Final Amplifier?" 

Unfortunately, that subject is much too 
broad for us to examine in any detail, so 
we'll have to strike some medium. We can 
start by asking "How Can Harmonics Be 
Controlled?", which will wrap up FCC 
questions 61 and 78. This will also tie 
directly into another question, "How Does 
the Antenna Circuit Affect the Final 
Stage?", which will take care of FCC ques- 
tions 40 and 62 among other points. Now 
we have only the FCC question 50 to cover, 
and we can get it by asking "What Happens 
in a Modulated Amplifier?" Actually, a large 
part of this question was answered in our 
previous installment, but question 50 is one 
which can be rather tricky as it has no single 
specific answer, so it's worth going into 
again. 



88 



73 MAGAZINE 




By this time, we'll assume that you have 
been following this course for some time, 
and weMI assume that you already have a 
pretty fair idea of what goes to make up the 
final rf stage of an AM, FM, or CW trans- 
mitter. What we have to say here also 
applies, with some exceptions, to SSB 
linears-hut we've already discussed them as 
a species apart. 

Ready to explore the depths of the 
harmonic problem? Lefs get under way. 



SATURATION 



CUTOFF 



OPER BIAS 




TlNPUT 



IpMAX 



distortion involves the creation of at least a 
small amount of harmonic signaL 

Even if we had perfect amplifiers, the 
only possible harmonic-free amplifier would 
be one operating in Class A, This would, in 
itself, rule out the harmonic-free amplifier 
tor any appreciable power level in transmit- 
ters, because Class A amplifiers are only 
about 25% efficient at best. To produce 
large amounts of rf energy and stay within 
our power limits, we must use Class B or 
Class C circuits. 

And by the nature of their operation, 
Class B and Class C amplifiers are prolific 
generators of harmonics. The Class C ampli- 
fier, in particular, clips off its input signal 
sharply at the bottom when cutoff level is 
reached, and equally sharply at the top when 
the amplifier's saturation point is reached 
(Fig. 1). The result is that only a small pulse 
from the original input signal gets through 
the amplifier. Any pulse with sharp corners 
contains a large amount of harmonic energy; 
the sharper the corners, the more high-order 
harmonics are present (the limiting case of 
this is a perfect square wave, which contains 
the fundamental and all the odd-order har- 
monics out to the umpty-umpth). 

If we reduce the level of the input signal 
to avoid saturation s and decrease the grid 
bias so that cutoff isn't reached quite so 
rapidly, we can reduce the sharpness of the 
clipping action. But while we're doing so, 




Ip 0, 



OUTPUT 



Fig. 1. Class C waveforms. 

How Can Harmonics Be Controlled? We 
have only two avenues of attack in any 
effort to control harmonics— one is to pre- 
vent them from being created in the first 
place, and the other is to prevent them, once 
created, from getting out of our transmit- 
ters. 

It might appear simple, at first, to operate 
an amplifier in such a manner that no 
harmonics were generated. And it might 
actually be simple, if there were any such 
thing as a perfect amplifier. We, however, 
must get by with imperfect amplifiers and 
their resulting distortion -and any form of 



SATURATION 



CUTOFF 



OPER BIAS 




MAX 




OUTPUT 



Fig. 2. Class B waveforms. 



MAY 1970 




we*re changing the amplifier from Class C to 
(lass B operation (Fig, 2) and reducing its 
efficiency. When we have completely elimi- 
nated the saturation-point clipping, and 
moved the cutoff clipping point down so 
that we get the positive-going half-cycle of 
input signal through to the output and lose 
only the negative-going half-cycle, we have a 
true Class B operation. 

If we keep reducing bias until no clipping 
at all occurs, we can get rid of much of the 
harmonic encrgy-but we will have con- 
verted our amplifier to Class A (Fig. 3) in 
the process and our efficiency is virtually 
gone. 

SATURATION 



OPER BIAS 



CUTOFF 




MAX 




OUTPUT 

Fig. 3. Class A waveforms. 

The point is that the high efficiency of 
the Class C circuit has its price, and that 
price is the high percentage of harmonic 
energy present in the output. In fact, most if 
not all of the added power in a Class C amp's 
output las compared to a similar circuit and 
input power operating in Class A) is com- 
posed of that harmonic energy! 

What saves the day for us and makes the 
(lass G circuit practical is the selectivity of 
the plate tank circuit. Like any other tuned 
circuit, the plate tank rings readily at its own 
resonant frequency, and tends to bypass all 
other frequencies. In the process of by- 
passing the harmonic energy, it is temporar- 
ily stored in either the magnetic or electric 
field of the lank, and adds to the output 
power at the fundamental frequency. 

When we use the phrase "fundamental 
frequency" here, we mean the frequency to 
which the plate tank is tuned, which is not 
necessarily that of the input signal. 



A case in point is the "frequency multi- 
plier" circuit so necessary to VHP and UHF 

transmitters. This is, in essence, just a Class 
C amplifier in which the output tank is 
tuned to some harmonic of the input fre- 
quency rather than to the input frequency 
itself. 

The efficiency of the frequency multi- 
plier is low, compared to that of a N \slraiglU- 
through" amplifier, because as the harmonic 
order rises, the amount of that harmonic 
present in the plate waveform falls. Thus a 
two-time multiplier is about half as efficient 
as a straight-through circuit, a 3-time multi- 
plier about a third, and so forth. 

To get the maximum efficiency out of a 
multiplier, we change its operating condi- 
tions just a little from those for a straight - 
through circuit. The most major change is to 
increase the grid bias. This increases the 
clipping action at cutoff, and boosts the 
harmonic content of the output by making 
the clipping more sharp. 

We can take a trip troni this to find ways 
of reducing the harmonic content of a Class 
C amplifier's output. Reducing the grid bias 
to the lowest level that will permit desired 
operation will help cut down the harmonics, 
as will trimming grid drive back to the 
lowest necessary level. And by all means, we 
should make certain that our plate tank 
circuits are tuned to the desired frequency, 
It's not too uncommon for Novices to 
accidentally tune to the wrong dip, but 
that's not what we're talking about so much 
as the possibility of an unwanted additional 
resonance at or near some high-order har- 
monic such as the seventh, ninth, or elev- 
enth. Such a resonance can result in a 
surprising amount of harmonic output from 
an otherwise clean transmitter. Careful 
probing of tuned circuits with a dipper is the 
best lest for such goings on. 

Since the selectivity and flywheel effect 
of the plate tank circuit in a Class C 
amplifier is the only thing standing between 
you and an overdose of harmonics, the tank 
circuit itself is a key factor in harmonic 
prevention. 

For best selectivity, and the companion 
condition of minimum harmonic energy, the 
of the plate tank should be high. Like the 
matter of circuit efficiency versus harmonic 



90 



73 MAGAZINE 




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generation, though, this is only one side of a 
tradeoff. High Q in a tank circuit means that 
the current circulating in the circuit will also 
be high; the circulating current in any tank 
with appreciable i-s equal to Q times the 
current going through the circuit to outside. 
That is, if your final is operating with a rms 
rf current of 1 00 ma (relatively low for a 
transmitter, since with a 600-volt supply this 
is only about 60 watts of rf), then if the 
tank circuit were equal to 100 the 
circulating current in the tank would be I 00 
X 1 00 ma, or \Q amperes, II (he resist a nee of 
the coil were only 0.1 ohm. the power lost 
in this resistance would be r R, or 1 x I x 
0.1 watts, which works out to 10 wan n 
nearly half of the total power produced by 
the amplifier! 

Reducing the tank circuit Q to 10 in the 
preceding example would reduce circulating 
current to 1 amp, and the lost power would 
drop to 0.1 watt; cutting Q to 1/10 its 
original value trimmed the loss to 1/100. 

So for minimum loss in the tank circuit, 
Q should be low, but for minimum har- 
monics, should be high. In practice, the Q 

MAY 1970 



of the tank is chosen as a compromise 
between these conflicting requirements, and 
normally lies in the range from 10 to 20 
i Fig. 4L A Q of 10 is about the minimum 
capable of providing decent harmonic rejec- 
tion, but at frequencies above 2\ mhz it 
often proves impossible to get down this low 
and a figure as high as 20 must frequently be 
accepted as the mini mum possible value. 

Note that these Q figures are the loaded 
of the complete tank circuit: don't get 
them mixed up with rhe Q ratings of the 
lank coil alone. The coirs Q must be as high 



t 



(00 
90 
60 
TO 



% 
HAflMOMC 

GO 

(RELATIVE) 

50 



40h 

30 

20 

10 






-30 



Fig. 4. Relative harmonic reduction for various 
plate circuit Q values. 



91 




. 



as possible in order to keep losses down. 
When the entire circuit is hooked up and 
loaded to the desired output level, it behaves 
as if a resisior were connected in parallel 
with it. Tills resistor (fictional, of course) is 
how the output power is accounted for in 
the circuit equations, and the "loaded Q" 
about which we're talking is the ratio of this 
fictional resisior and the reactance ni reso- 
nance. 

If loaded is too small, harmonic prob- 
lems are not the only troubles to be 
expected. The circuit will also prove difficult 
to couple to a load. Loaded Q can be 
increased by reducing the inductance in the 
circuit, or increasing the capacitance. The 
loaded Q of a final -amp lank will also vary 
with the coupling to the antenna: all calcula- 
tions are based on the assumption that the 
amplifier is delivering its intended output 
power level. If more lightly loaded, will he 
higher, and if overloaded, Q will drop. 

Since each tuned circuit adds additional 
rejection of off -frequency signals while 
having little effect on signals at the resonant 
frequency, the more tuned circuits you have, 
the smaller will be the harmonic content of 
the output. This is an excellent reason for 
use of antenna tuners, Harmonic filters, 
about which we'll have more to say a little 
later, are in the final analysis merely special 
kinds of tuned circuits, 

Because additional tuned circuits offer 
additional harmonic rejection, any trans- 
mitter making use of frequency multiplier 
stages (which means, in practice, almost any 
transmitter except a sideband rig) should 
have the multipliers as early in the lineup as 
possible. This permits the maximum number 
of tuned circuits to follow them, thus 
attenuating the unwanted harmonics pro- 
duced by the multipliers while strenghtening 
the desired output frequency. 

The multipliers should also be operated at 
the lowest power level practical for them; all 
power gain should be achieved in straight- 
through stages if possible. At VHF and UHF, 
this is not always practical, due to the 
difficulties of attaining large amounts of 
power amplification at these high frequen- 
cies, but in hf transmitters the rules are to 
keep the multipliers early in the lineup, and 
operate them at low power. 



So far we've examined only the theoret- 
ical and design considerations involved in 
minimizing harmonics. Construction prac- 
tices, however, are of at least equal impor- 
tance. Since ifs impossible to avoid having 
at least a little harmonic energy inside a 
transmitter, and the theoretical cures are 
based on keeping it inside without permitting 
it to be radiated, the construction must 
contribute to keeping the harmonics sealed 
up. 

One of the first steps is to employ 
adequate and carefully installed bypass capa- 
citors on all signal return paths, since the 
unwanted harmonic energy must flow 
through a complete circuit and a poor 
bypass may permit the harmonic to find an 
easier path out by means of the normal 
output circuit. If the lead inductance of 
these bypass capacitors cannot be made 
negligible by reducing lead length to almost 
zero, then it should be adjusted to form a 
..Ties resonant circuit to ground at the 
frequency of the most troublesome har- 
monic. This will minimize that one har- 
monic, at least. 

A companion step, equally nee ary, is 
to shield alt rf stages adequately, To be 
adequate, the shielding must he complete, 
No gaps must exist through which harmonic 
energy may leak outside the rf section. This 
means not only that meter holes and the like 
must be shielded, but that all joints in the 
shielding enclosure be rf-l t. Finger stock 
or metallic sponge is usually necessary at all 
doors or other openings in the enclosure in 
order to meet this requirement. 



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Fig. 5, How wires through shielding defeat the 
shield, and how to cure them. 

Before shielding can be considered com- 
plete, al! sources of leakage through the 
shielding must be plugged. This includes all 
wires going through the shielding (Fig, 5). 
Any lead passing through the shield should 



92 



73 MAGAZINE 






be appropriately filtered to be certain that it 
carries only I lie desired energy through, and 
that all undestred energy remains trapped 
inside the shield. This in cans careful by* 
passing of all dc and power conductors 
(often using coaxial or feed through capaci- 
tors where the conductor passes through the 
shield), and appropriate tillering of signal 
leads. 

When shielding is complete, nothing but 
dc and power can get into an rf enclosure, 
and nothing hut rf at the desired output 
frequency can get out. What is more, Hie 
only way this rf can get out is through the 
antenna connector (even the antenna con- 
nector is considered to be a gap in the 
shielding- the shielding is kept complete by 
the coax shield when coax feed lines are 

used) 

Complete shielding helps keep a trans- 
mitter from radiating harmonics through 
undesired ports, hut does nothing in itself to 
reduce the quantity of harmonic energy 
present in the output signal. To reduce the 
amount of harmonic energy going out 
through the antenna connector, several more 
points of circuit design and construction 
should be considered: 

The various stages can be coupled by any 
of several means. One of the most conve- 
nient, and so one of the most often used, is 
"capacitor coupling" where an rf choke or a 
tuned circuit offers high impedance to the 
signal in the output circuit of the preceding 
stage, and a capacitor provides a low- 
impedance route for this signal to the input 
circuit of the following stage. This circuit, 
shown in Fig, 6, is one of the least desirable 






RFC 



Fig. 6. Capacitor coupling between rf stages, 

of all means of coupling so far as harmonics 
are concerned, because harmonics can 
couple from one stage to the next even more 
readily than can the desired signal when 
capacitor coupling is used. 

Several other means also exist for cou- 
pling stages, One is "link" coupling, where 



l lie output of the preceding stage is coupled 
to a pickup link which is in turn connected 
to a second link, and the second link couples 
to the input of the following stage as shown 
in Fig, 7. This circuit discriminates against 
harmonics, because the coupling is most 
effective only at the frequency to which the 
two luned circuits arc tuned. 




Fig. 7. Link coupling. 

Another method is shielded inductive 
coupling, shown in Fig. 8. Here, the two 
tuned circuits are coupled directly to each 
other rather than through links, but an 
electrostatic shield between them (the 
"Faraday screen") blocks any capacitive 
transfer of harmonics from one to the other. 



FARADAY 
SCREEN 





Fig. 8. Electrostatically shielded inductive cou- 
pling. 

Combining these two methods gives us 
"shielded link" coupling, which is particu- 
larly effective against harmonic transfer. It is 
the same as link coupling, except that each 
link is electrostatically shielded from its 
associated coih Unfortunately, this tech- 
nique is often considered too cumbersome 
for ham use. 

Possibly the most effective of all inter- 
stage coupling schemes, so far as harmonic 
rejection is concerned, is the use of a 
pi-network as shown in Fig. 9. The pi- 
network is, in essence, a low-pass filter and 
so it tends to actively filter out all har- 
monics. At the same time, it provides an 
effective coupling path for the desired signal. 
If designed properly, it can provide as 
effective coupling as any other system. 
However, it does require careful design or it 
will not transfer as much signal energy as the 






MAY 1970 



93 





Fig. 9. Pi-network interstage coupling. Note resem- 
blance to low-pass filter circuit. 

simpler forms. This apparently the main 
reason it has not found more use in ham 
circuits, the majority of which use either 
capacitor or inductive coupling with no 
particular effort to minimize harmonics. 

Once the harmonic energy reaches the 
output connector of the transmitter, it's still 
not too late to keep it from being radiated. 
Adding tuned circuits by means of antenna 
couplers will reject some harmonic energy. 
Most hams, however, use low-pass filters in 
the feedline. These filters reject all energy 
above their cutoff frequency. 

Low-pass filters of the most common 
design are effective against those harmonics 
which cause TVI, but have little or no effect 
on such things as out-of-band harmonics at 
lower frequencies (such as the second har- 
monic of a 3990 khz phone signal at 7980 
khz, outside any ham band). 

A less common design called the "Har- 
moniker" consists of a half-wave trap filter, 
and works very much like a set of tuned 
circuits to pass only the fundamental signal 
and block all other harmonics. The disadvan- 
tage, to the operator, of such a filter is that 
each such filter is effective for only a single 
band. When the band is changed, a different 
filter must be put into the line. The ordinary 
low-pass filter, with its cutoff frequency in 
the neighborhood of 45 mhz, permits all 
signals in the hf ham bands to pass and so 
need not be changed for operation from 3 to 
30 mhz. 

No discussion of harmonic control could 
be complete without some examination of 
the final "filter" in the transmitter system— 
the antenna itself. 

An ordinary dipole antenna is effective 
only for the band for which it is cut 
(although the ordinary dipole is also usable 
to a lesser degree at the third-harmonic 
frequency as weU), Many other antenna 
designs share the "single-band" characteristic 



of the half -wave dipole. Use of such single- 
band antennas provides a final filtering 
action against unwanted harmonics, since 
even if they are generated and get through 

■ 

all the other filters and tuners up to the 
antenna itself, they still will not radiate 
efficiently. 

Multi-band antennas, on the other hand, 
offer no such filter action. Since the ham 
bands are in harmonic relation to each other 
in the hf region (even 21 mhz is the 3rd 
harmonic of 7 mhz), any antenna capable of 
radiating efficiently on all hf ham bands 
must be able to radiate on at least one 
harmonic and frequently on several har- 
monics of any particular operating fre- 
quency below the 10 meter band. 

Thus, when maximum control of har- 
monics is required, the transmitter must be 
designed to minimize them in the first place, 
then constructed with complete shielding 
and bypassing, operated with proper bias 
and drive to keep harmonics low, and 
connected to a single-band filter. Few ham 
stations require this extreme degree of con- 
trol-but it can be achieved. 

How Does the Antenna Circuit Affect 
the Final Stage? We all know lhat in any 
transmitter the antenna circuit plays a large 
part in the operation of the final rf amplifier 
stage. Any troubles or problems in the 
antenna or feedline usually manifest them- 
selves in the form of problems in the 
transmitter as well. What we're setting out to 
discover here is how this interaction between 
antenna and final rf stage occurs, and why. 

To do so, let's begin by looking not at the 
final rf stage, but at some earlier stage. It 
doesn't matter which one, because what 
we're going to examine is the general work- 
ing principle of an rf power amplifier. 

The purpose of any rf power amplifier is 
to accept an input signal of some sort, 
together with dc power from the power 
supply, and to produce from these two input 
ingredients an output signal which is a 
magnified copy of the input signal, identical 
in all respects except at a greater power level 
(if the amplifier happens to be modulated, 
the output won't be identical -but it will 
depend on the rf and af input signals in that 
case). 



94 



73 MAGAZINE 



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The input signal comes from some driving 
source, and the output signal is delivered to 
some "load." Until the output signal gets to 
the load, it can't be considered as "output" 
because it hasn't yet left the amplifying 
stage. 

The normal load for an rf amplifier in the 
driver stages of a transmitter is still another 
rf amplifier. To get the signal from one state 
to the next, the two stages must be coupled 
together by some means. The normal means 
uses tuned rf circuits. 

These tuned rf circuits also play a part of 
the role of the "load" for the driving 
amplifier, so far as the tube itself is con- 
cerned. The plate tank circuit has some 
specific value of impedance, and this value 
of impedance furnishes the load against 
which the plate current of the amplifier tube 
"pushes" to develop the output power. 

But tuned rf circuits are rather tricky 
things; their impedance isn't so easy to 
define as is that of a simple resistor, because 
the impedance of a tuned rf circuit involves 
such things as transformer action between 
input and output, stray capacitance, self- 



inductance, and the amount of power taken 
out of the circuit (which acts, effectively, as 

resistance inserted into the circuit, and 
modifies the circuit Q). 

For this reason, the driven stage influ- 
ences the operation of the driving stage. We 
say that the two stages are not isolated from 
each other, or that they interact. We may 
find, for example, that adjusting the plate 
tank of one stage may change the plate 
current of some earlier stage. We are almost 
certain to discover that a change in the grid 
tuning of one stage will affect the plate 
tuning of the previous stage. 

This interaction between coupled stages is 
true of all rf power amplifiers. Some circuits 
provide less interaction than others (notably 
the grounded-grid arrangement), but it's 
always present to some degree. 

Now let's go back to the "final" stage. It 
still must furnish power to a load, but now 
the load is an antenna circuit rather than 
being just another amplifier stage. 

The interaction, however, is still with us. 
Any change of impedance in the antenna 
circuit reflects back into the final tank 






MAY 1970 



95 



circuit of the transmitter, and affects its 
adjustment. The effects may be minor, or 
they may be catastrophic— it all depends 
upon the particular situation. 

For any if power amplifier to operate as 
designed, the operating conditions intended 
by its designer must be present. One of these 
operating conditions is the appropriate value 
of load impedance. 

If the load impedance is too low, or too 
high, the amplifier won't operate as 
intended. Too high a load impedance pre- 
vents as much of the power getting out of 
the circuit as was meant to, and may cause 
severe damage. For example, operating a 
beam-power stage into an open-circuit load 
produces extremely large swings of plate 
voltage in" the tank circuit. These swings 
affect the plate-screen voltages in such a 
manner as to greatly increase screen current, 
and it's not uncommon to find the screens 
of such tubes vaporized by any extended 
period of zero-load operation. 

Too low a load impedance pulls down the 
Q of the final tank circuit and reduces the 
effective impedance seen at the plate of the 
tube. This removes the only limiting factor 
determining plate current, and again the 
lube may be destroyed; the main difference 
is that it's either the plate or the cathode 
which goes in this case. 

These are, of course, extreme examples, 
But excessive swr on antenna feed lines, 
caused by improper feedline termination, 
can approach these conditions. The resulting 
improper operation can pop coupling or 
bypass capacitors, cause tuning components 
to arc over or melt, and burn out tube 
elements. 

The direct means by which the antenna 
gets into the act at the final amplifier is 
because it provides the "resistance" into 
which the final's output power is accounted 
for. So long as the antenna acts as a pure 
resistance (or at least acts thay way at the 
point where the transmitter sees it), the 
transmitter can be adjusted to deliver its 
intended output power. If the transmitter is 
designed to operate into a 50 ohm resistive 
load and the antenna looks like 50 ohms of 
resistance, all is well. 

If the transmitter expects a 50 ohm load 
and the antenna looks like 100 ohms: of 



resistance, then only half as much power as 
expected can be transferred at the design 
settings of the transmitter. 

But increasing the coupling between 
antenna and plate tank circuit, by either 
changing the number of turns of the position 
of the coupling link, or changing both 
inductance and capacitance values if the 
transmitter uses a pi-network output circuit, 
can produce the intended impedance trans- 
formation and restore normal operation. 

If, on the other hand, the antenna 
appears to be a 25 ohm resistor, then the 
coupling must be decreased by moving the 
coupling link farther from the tank coil, 
using fewer turns on the link, or again 
changing values in a pi-net. 

A more satisfactory solution to either 
situation is to use an external antenna 
coupler to transform the antenna's resistance 
into the 50 ohms of resistance the trans- 
mitter expects. 

If the antenna does not look like pure 
resistance, but has either inductance or 
capacitance as well (it cannot have both L 
and C, because the larger will cancel out all 
of the smaller), things get more complicated. 
The reactance of the antenna will be coupled 
back into the final tank circuit, because the 
coupling means between final tank and 
antenna is essentially a transformer and 
transformers work both ways. This will 
detune the final tank to one side or the 
other of the desired frequency. When the 
tank is retuned to cancel out the antenna 
reactance, the coupling may no longer be 
correct, and when the coupling is changed, 
more detuning may occur. The net result is, 
at best, a compromise. 

Even if the antenna itself is a pure 
resistance at the operating frequency, a 
mismatch between feedline and antenna will 
produce reactance in the line. The reactance 
may be either inductive or reactive, depend- 
ing entirely upon the length of the feedline 
in terms of wavelength, 

If the antenna itself has inductance, or 
capacitance, at operating frequency, then 
the feedline cannot match it. Line reactance 
in this case, though, depends upon the 
reactance of the antenna as well as upon 
feedline length and cannot easily be pre- 
dicted. 



96 



73 MAGAZINE 






No matter how much reactance is present 
in a feedline, it will look like a pure 
resistance at a series of points 1/4 wave- 
length apart along its length, tf the antenna 
is a pure resistance but mismatched in 
resistance value to the line, these points will 
be every 1/4 wavelength back from the 
antenna. If the antenna has reactance, then 
the location of the first point cannot easily 
be predicted-but once it is found, the 
resistive points will recur every 1/4 wave- 
length back toward the transmitter. 

The resistance at these points, in either 
case, may be very high or very low. It will 
never be equal to the line's rated impedance 
unless the line is matched to the antenna — 
and in this case every point along the line 
will show that same resistance. 

For instance, a 50 ohm line connected to 
a 100 ohm antenna will have a vswr or 2 to 
1. One quarter wavelength back from the 
antenna, the resistance will be 25 ohms. 
Another quarter-wave back, the 100 ohm 
antenna resistance will lepeat. From there 
on back to the transmitter, the 25 ohm and 
100 ohm values will alternate. The rule is 
simple in such a case; at the antenna, the 
antenna resistance occurs. This defines vswr 
as Ant/Line or Line/Ant, whichever provides 
a result greater than 1. Let's assume that the 
antenna resistance is greater than that of the 
line, so we use Ant/Line. 

A quarter wave back, the resistance 
equals line resistance divided by vswr, A half 
wave back (two quarter waves), the resis- 
tance is that of the line multiplied by vswn 
Thus at odd multiples of 1 /4 wavelength, the 
effective resistance is that of the line divided 
by vswr, and at even multiples (or half-wave 
multiples), it is that of the line multiplier by 
vswr. 

The same rule applies even if the antenna 
is reactive. The resistive points will be either 
at line resistance divided by vswr, or line 
resistance multiplied by vswr, depending 
upon their distance from the first resistive 
point and its relation to the line resistance. 
Fig. 10 illustrates this rule. 

Now let's consider a 50 ohm line with a 
10-to-l vswr. The pure-resistive points will 
be either 5 or 500 ohms. Both these values 
approach the extremes of short-circuit or 
zero-load conditions, if they appear at the 



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LEM3TH-* 



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t 



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_t_ 







REACTANCE 

L 





X SWR 

RESISTANCE 

NOMINAL 

/ SWR 



Fig. 10. Relation of feedline impedance to length 
of feedline, 

antenna connector of our transmitter. 
Component damage is most likely. 

In practice, we normally avoid such 
extremes by "pruning" the feedline so that 
its resistive component is somewhere near 
that for which the transmitter is designed, 
and then accepting the detuning effect of 
the accompanying reactance. This often 
works well. Again, an antenna tuner or 
coupler is better practice, because no detun- 
ing results. 

In some cases, and with some final- 
amplifier output circuits, even a very small 
value of swr is adequate to upset circuit 
operation. Most affected by swr, surprisingly 
enough, is the popular pi-network output 
circuit. 

The pi-network is billed as being capable 
of matching feedlines from 10 to 600 ohms 
when designed for 50 ohm operation, and 
this is true enough if the feedlines are 
resistive. However, the pi-network is a rather 
complex device which acts by transforming 
impedances, and one of its critical para- 
meters is the capacitance present in the 
output side of the circuit. This parameter, in 
fact, establishes the value of the impedance 
transformation, which allows it to be used as 
a "loading control." 

If the feedline contains reactance, the 
reactance may be either inductive or capaci- 
tive, If the reactance is inductive, it will 
cancel out a part of the output-capacitor's 
capacitance, and thus increase the loading. 
Such a feedline appears to load quite readily 
on a pi-net rig, and if the effect is not too 
severe this may be no disadvantage at all. 
However, a little too much inductance here 
may make it impossible to get loading down 
to design value. 

If, on the other hand, the feedline reac- 
tance is capacitive, it will add to that of the 



output capacitor and thus reduce the load- 
ing. In this case, it may not be possible to 
make the antenna accept the full power 
output of the transmitter. 

The cure in either case is simple; remove 
the reactance from the feedline. This can be 
done either by pruning to some different 
length (while this may not remove the 
reactance, it will certainly change it and the 
change may help), or by using an antenna 
tuner. 

Now that we've seen how the antenna 
circuit can interact to change the operation 
of the transmitter's final stage, let's look 
again at that final stage operation. The stage 
was designed by someone, originally, who 
had some definite operating conditions in 
mind for it. Even if you designed it by 
taking a published circuit and varying things 
here and there to fit the content of the junk 
box, whoever did the original design behind 
the published circuit had definite operating 
conditions intended. 

Some of these operating conditions 
include grid bias, grid current, driving power, 
plate voltage, plate current, screen voltage, 
screen current, and output power. 

Because of the interaction of the antenna, 
especially in its effects upon output power, 
plate current, and screen conditions, almost 
all designs include provisions for varying the 
coupling between final stage and antenna. 
These range from a simple variable link 
which may be adjusted to be near the final 
coil (maximum coupling) or far away (mini- 
mum coupling), through the combination of 
a link and tuning capacitor (in this case the 
capacitor often serves as a coupling control 
and the link position is fixed), to the more 
complex pi network which may have one, 
two, or three adjustments. The coupling is 
intended to be adjusted as a part of the 
operating procedure, to provide the proper 
load for the final amplifier tube. 

This leads immediately to the question 
"How do we know when coupling is cor- 
rect?' 1 , but the answer is simple— correct 
coupling produces the design levels of input 
and output voltages and current, with the 
design level of input power and the rated 
output power. In other words, whenever 
everything else is right, you know the 



98 



73 MAGAZINE 






coupling is right also— and if the coupling's 
wrong, something else will be wrong to show 
you. 

What Happens in a Modulated Amplifier? 
In our previous installment, we examined 
the goings-on inside a modulated amplifier in 
considerable detail. We did not, however, 
delve very deeply into what happens in case 
various power supplies were to be suddenly 
short-circuited. 

In some cases, of course, shorting of a 
power supply would simply lead to rather 
spectacular fireworks (particularly if the 
plate supply of a full kilowatt rig were to be 
shorted out, and to a lesser degree with the 

plate supply for any other device, or any 
screen supp.yl. 

In others, though, and especially if the 
power supply were intended to provide 
voltage rather than power, the effect upon 
the power supply itself might be negligible. 
The question then would become what 
would happen to the amplifier, and how 
would the short affect its operation. 

The particular case we're studying is, of 
course, that cited in the FCC study list- 
shorting out the grid bias supply of a Class C 
modulated amplifier. The principles, how- 
ever, apply to all supplies in which similar 
conditions prevail. 

As we saw last time around, the bias 
requirements for a modulated Class C ampli- 
fier vary from moment to moment during 
the modulation cycle* Since the require- 
ments are changing so rapidly, it's not 
possible to manually adjust the bias voltage 
for optimum conditions at each instant. The 
way around this problem is to make the bias 
self-adjusting, by using grid-leak bias to 
provide a major part of the operating bias 
voltage. 

But when this is done, the fixed bias 
supply assumes a subsidiary role. Its major 
purpose, now, is merely to provide protec- 
tion for the amplifier circuit in case the drive 
should be removed and so take away the 
grid-leak bias voltage. 

When such a combination of fixed "pro- 
tective" bias and grid-leak-derived "opera- 
ting" bias is involved, the effect of shorting 
out the fixed bias supply will depend 
entirely upon the ratio between fixed and 
grid-leak bias. If the fixed bias is a small 



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99 



portion of the total operating grid voltage, 
loss of the fixed bias supply would have 
almost no effect upon the circuits operation 
so long as drive was available to the stage. 
The only way, in fact, that its loss could be 
noted would be to remove drive and watch 
plate current skyrocket out of bounds. 

If, on the other hand, the fixed bias 
provides an appreciable portion of the total 
operating grid voltage, with only enough 
extra bias derived from the grid leak to 
provide a measure of self-adjustment, then 
loss of the fixed bias supply would quite 
probably totally upset the amplifier's opera- 
ting conditions and might even move its 
operation from Class C down to the Class B 
region, This would result in horribly dis- 
torted output, due to the drastic change in 
amplifier operating conditions. 

Damage to the bias supply itself caused 
by a sudden short would depend upon the 
amount of current limiting designed into the 
supply. Most rectifiers will stand a very small 
momentary overload; to prevent long-term 
overloads, current-limiting resistors are gen- 
orally connected in series with them, In 
supplies intended to deliver large amounts of 
power, these limiting resistors are small. In 
supplies delivering voltage but little power, 
the resistors are often much larger, specifi- 
cally to protect against accidental shorting 
of the output. 

The actual lack of necessity for fixed bias 
at all on a modulated Class C amplifier is 
demonstrated by the number of amplifier 
designs which completely omit fixed bias 
from all stages. Operating bias is obtained 
entirely from grid-leak resistors, and circuit 
protection is provided (if at all) by "clamp 
tubes" which act to drag screen voltage 
down to safe values if drive is lost and grid 
bias disappears. In an amplifier of this 
design, the whole question concerning bias- 
supply short-circuits becomes rather mean- 
ingless. 

In a broader sense, though, the question 
still applies even if no fixed bias supply is 
present. Failure of the grid-leak resistor, or 
loss of drive, for example, can cause the 
operating bias to be sharply reduced or even 
to disappear. 

When this happens, the effect upon cir- 
cuit operation is catastrophic. If drive is lost. 



then no output can be expected and the 
entire transmitter is dead. If the resistor fails 
completely, the same situation occurs. If the 
resistor suddenly changes value, the trans- 
mitter may continue to operate but the 
operating conditions in the output stage 
have been completely changed and the 
chances of satisfactory operation are small. 

The effects upon circuit components in 
such a case are at least as catastrophic. In a 
Class C amplifier, grid bias is normally the 
only factor limiting current in either the 
plate or the screen circuits. When bias 
disappears, both plate and screen current 
shoot skyward. Unless extremely rapid- 
action fuses are included in the circuit (and 
sometimes even then) the least you can 
expect is damage to the plate and screen 
milliammelers, ranging from bent needles to 
total burnout. If the overcurrent is allowed 
to persist for any appreciable period of time, 
and if fuses or meter burnout does not 
interrupt current flow, the tube itself will be 
damaged or destroyed. Along the way, any 
resistors, rf chokes, or coils in the path of 
the excessive current are also subject to 
damage. 

In the absence of either fixed protective 
bias or clamp tubes, one scheme remains 
available to help protect things in case of 
bias loss. This is to provide a small amount 
of fixed bias by means of a cathode resistor. 
While cathode biassing is conventional prac- 
tice in audio circuits, it is seldom employed 
in rf amplifiers for one major reason— in 
order for an rf power amplifier to operate 
properly, the cathode must be at ground 
potential With a cathode bias resistor, feed- 
back between grid and plate circuits is 
inevitable unless extremely effective bypass- 
ing is present. And as it happens, it's almost 
impossible to get bypass capacitors effective 
enough to work with cathode bias, since the 
bias resistance is relatively small and a 
bypass, to be effective, should have less than 
1/10 and preferably less than 1/100 the 
impedance of the element being bypassed. 
Rather than attempt to develop capacitors 
with impedances below 0.1 ohm, most 
designers simply avoid cathode resistance in 
rf power circuits. 

- . . Staff 



100 



73 MAGAZINE 



1 



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Phone 205-84 M 789 



— 




ven with the large choice of SSB gear 
on the market today, there are still 
many amateurs who enjoy transmitting and 
receiving a well modulated AM earner. This 
is especially true in the field of mobile 
radio. 

A quick check of 10 meters will show 
that AM QSOs are available in number, and 
that most are from mobiles running low 
power. If you haven't done so lately, listen 
in around 29 MHz, and then sit back and 
recall when you used to be in there with 
the best of them. 

For the ham who enjoys "rolling his 
own," AM mobile is a natural. It's even 
more so nowadays, what with printed 
circuits and ICs, because they can reduce 
the size of the gear. Each of us has his 
favorite transmitter and converter circuits, 
and the old reliables for antenna switching 
and control circuits. However, the one area 
that usually gets short-changed, or simply 
avoided, is noise limiting. 

When you scan through today's ham 
journals, you quickly discover that the 
basic methods for noise suppression 
haven't changed too much over the years. 
Limit ers for converters work well in gen- 
eral, if you're willing to pay the price of 
modifying the car BC set. This usually 
involves tearing out the detector stage, 
rewiring it. and then somehow stuffing the 
added parts into the BC set wherever you 
can find the space. 

Just about the time I had almost given 
up on the idea of 10 meter mobile, because 



I'd have to install a series limiter, 1 ran 
across an old copy of Editors and 

Engineers Handbook. In it was a circuit 
that looked like it would do the job, be 
inexpensive to build, and above all, would 
be easy to install. Oldtimers will recognize 
the diagram as the Bishop noise limiter. 

Being a shunt-type I i miter, it simply 
hangs across the last i-f stage in the BC set. 
It's self-biased and automatically adjusts to 
the degree of niodulation. The bias-circuit 
time constant is determined by CI and the 
shunt resistance, which consists of Rl and 
R2 in series. The plate resistance of the last 
i-f tube and the capacity of CI determine 
the charging rate of the limiter. It can be 
disabled by opening S 1 , which allows the 
bias to rise to the value of the i-f signal. 

So much for the little theory involved, 
because as we all know, the big question is 
how well is it going to operate under 
individual circumstances? In my installa- 
tion, a tube-type converter is used ahead of 
the car radio. With the limiter in the 
circuit, and engine speed at about 25 miles 
an hour, the noise limiting was better than 
I expected. 

However, when the cruising speeds of 
60 or 70 mph were reached, the limiter was 
"swamped out." It couldn*t handle the 
incoming pulses fast enough. As you've 
probably guessed, the problem was quickly 
cured by changing the R/C time factor. 
This is indicated by R x , where I paralleled 
two more 270 kfi resistors. These values, 
of course, were needed in my limiter, and 



102 



73 MAGAZINE 








the resistance will probably differ for 
yours. With that minor change, the limiter 
works as effectively at 70 mph as it does 
while waiting at a traffic light; 

As for the title of this article, it took 
about 27 minutes to install and wire the 
parts for the limiter. Fve never been able to 
install a series limiter in that small amount 
of time. The author would like to thank 
Bob, K7JSD, for his help during the "cuss 
and solder" stage of work. Bob is known 
locally for the crafty way in which he 
sweat-solders 7-pin sockets! 

Parts installation couldn't be much 
easier, I punched a hole in the rear lip of 
the BC set for the 12AL5> so that the tube 
could be installed after the set is back in 
the dash. Inside the receiver is a four-lug tie 
strip, on which the few parts are mounted, 



If you buy everything new, it'll cost about 
$3 ? including the 12AL5, 

Semiconductor diodes of the computer 
family were seriously considered at first, 
and we thought about using lN658s. 
However, they are more expensive, and I 
have a strong respect for the back resis- 
tance of the 12AL5 for this kind of 
application. 

There are many "peanut whistle" rigs 
on the high end of 10 meters nowadays, 
and it has been a pleasant experience to 
rediscover the fun of AM mobile. The 
limiter I've described will really help pull 
those other mobiles out of the noise leveL 
You may even find that after you've 
finished reinstalling that old mobile AM 
gear, you can kick the sideband habit! 

. . . W7SOH ■ 



LAST l-F 



455 KHz 




Fig. 2 p Bishop i-f noise limiter. 



MAY 1970 



103 




104 



73 MAGAZINE 



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Send to 73 Magazine. Peterborough. N. H. 03458 



MAY 1970 



105 



S am Kelly W6 JTT 
12811 Owen Street 
Garden Grove CA 92641 





A LOW 



BAND 





FOLIC 

MONITOR 



With the spectrum being shared by 
such agencies as state police, 

highway patrol, and the sheriff, there 
should be a lot to listen to * . . 




M~~ ~ onitoring police and emergency com* 
muniealions channels can provide 
fun and excitement, For effective moni- 
toring, the receiver must be stable, sensitive, 
cover several channels, and have a squelch. 
Tli ere are several monitor receivers on the 
market ranging from about twenty dollars to 
well over a hundred. 




Typical "Doghouse" receiver before modification. 

Fortunately, for those short of money, a 
good receiver can be had for a few bucks and 
a little work - at least for the 30-50 MHz 
band. "Doghouse" type receivers covering 
this band are still found in surplus stores for 
around $15. These receivers are all quite 
similar, having been built by Motorola, or to 
Motorola prints by various subcontractors. 



These sets use 13 octal tubes. Typical model 
numbers are R-237/B-VR. P-8028, and 
FMR-13. They all have a first i-f of 4 J MHz 
and a second i-f of 455 kHz. They are 
wideband (±15 kHz), single-channel, crystal- 
controlled units and nominally cover 30 40 
or 40-50 MHz. Typically the front ends use 
6SD7s or 6SG7s for oscillator, first mixer. 
and rf amplifier. 

The conversion consists of building an ac 
power supply, connecting the local controls, 
and converting the crystal oscillator to a 
tunable type, Depending on the frequency 
to be monitored, the rf and mixer coils may 
require pruning. 

First, remove the vibrator power supply 
by taking out the three large screws holding 
it to the chassis, disconnecting the red and 
yellow plugs, and lifting the supply off, The 
power supply shown in Fig, I is then built 



i nv 

IA 



IISV 



tOO mA 




/77 /77 



* RED 



250-0250 
100 mA 



S. 



YELLOW 



Fiq. 1 . Power Supply 



106 



73 MAGAZINE 




SQUELCH 




8 > 



3.2fi 

SPEAKER 



Fig. 2. Control Connections 

on the chassis in the space vacated by the 
vibrator power supply. 

The controls shown in Fig, 2 are then 
wired in. At this point it is advisable to 
smoke-test" the set. Turn it on and check 
to see that the squelch and volume controls 
are operating properly. If you have a signal 
generator, feed a 4,3 MHz signal into pin 4 
of the first i-f to see if all the low- frequency 
stages are operating properly. Frequently the 
conversion crystal is missing. If so, the 
replacement crystal frequency is 4755 kHz. 

Figure 3 shows the before and after 
modifications made to the oscillator. At this 
point, o word is in order about frequency 
allocations. Most areas seem to group the 



local frequencies quite close together. In 
Orange County, California, for instance, 
most of the channels of interest lie between 
45.1 and 45.7 MHz. 

The front end of this set is good and 
broad, so rf tuning is not needed. In opera- 
tion, the slug of the oscillator coil is posi- 
tioned so that the tuning range of the 
oscillator is centered in the band of interest. 
A station in the center of the band is tuned 
in and the trimmers of L2 and T2 are peaked 
for best reception. Since all police trans- 
missions are now narrowband, some im- 
provement can be made by clipping the 
loading resistors from the primaries of T3, 
T4, and T6- The i-Ps are then peaked. 

If you have a 30^40 MHz receiver and 
want to cover the high end of the band, it 
will be necessary to remove one turn from 
L2 and T2 # 

Once you have the receiver working, you 
are ready for some serious monitoring. A 
well located antenna is a must. And omni- 
directional coverage with vertical polari- 
zation is very desirable. A good approach is 
to buy a CB base station antenna and trim 
the elements to your frequency of interest. 

This brings up the problem of how to 
find out what frequencies arc in use in your 
local area, and the codes. There are two 
ways to do this. The first is to visit your 
local police or sheriff's communication cen- 
ter and ask. If you are too timid, you can 
invest in a good listening guide. There are a 
number commonly available. 

. . . W6JTT" 




R53 '00 pF 




15 pF 




WAS 



IS 



L- 10 TURNS W24 SOLID ON 1/4 
SLUG TUNED CERAMIC FORM TAP 
AT 3 TURNS FROM GROUND 
WINDING SPACED 1/4" LENGTH 



MAY 1970 



Fig, 3. Oscillator Modifications 



107 



■ 




Mobile rig installed in the back of the car and 

showing antenna coil mounting. 




Top view showing the output coil and tuning 
capacitors* 




Ed Marriner W6BLZ 
528 Co lima Street 
La Jo /la CA 92037 




Side view shov/ing the power supply transistors 
and General Radio input terminals. 



MOBILE 



This is a description of a 50W (output l, 
self-contained, mobile CW transmitter, 
for the 80-40-20 meter amateur bands. The 
basic idea for a simple CW rig was to have 
i! available, and installed in the trunk of 
the car out of the way. 

The output power is sufficient to hold 
regular schedules back to home base, even 
on long trips when you can shift to the 14 
MHz band. For simplicity, plug-in coils 
were used for the oscillator, and a shorted 
coil for the output. Changing bands is not 
as difficult as it may first seem once the rig 
has been tuned up previously on each 
band. The cover is slipped off, the switch 
turned, and the coil exchanged for the 
other band and the knobs reset to the 
marked bands. The transmitter power can 
be turned on from a heavy-duty switch or 
by using a 12V dc relay from the driver's 
seat. A key can be mounted in the driver's 
compartment or strapped to the steering 
wheel. If a 5 — 10 k£2 dc relay coil is used, a 
low voltage battery of I5-22V will actuate 
it with the key, or you can tie into the car 
battery. 

Theory 

The crystal-controlled oscillator is a 
12BY7 tube, and the filament heats up in 
1 1 seconds. The oscillator has plenty of 
output to drive a 12DQ6 on all bands. This 
tube also heats very rapidly and both are 
more available and cheaper than quick 
heater filament type tubes in the 12V 
variety. The cathodes of both tubes are 



108 



73 MAGAZINE 





opened for keying so that the rig could be 
turned on just before the contacting 
station signs his call; thus with the tube's 
cathode open the oscillator does not inter- 
fere. A lOOO resistor and .01 capacitor 
across the key acts as a filter. 

To operate the set on 20 meters, a 7 
MHz crystal is inserted in the oscillator and 
the plate circuit tuned to 20m works as a 
doublen Normal operation on 40m would 
be to use a 7 MHz crystal, or you could use 
a 3.5 MHz crystal with the plate tuned to 
40m. Both work satisfactorily. If 80m 
operation is intended, a set of 80m crystals 
that will double into the 40m CW band will 
work out fine. 

The power supply uses a Triad toroid 
oscillator transformer which operates in 
the audio range, making filters very easy; 
no heavy choke is required. The whole rig 
and the 400-2 50V power supply fits on 
the chassis without crowding. 

Construction 

The transmitter and power supply are 
built on a California Chassis A- 147, 4 x 8 x 
2 in. General Radio terminals are sanded 
down to make a tight fit on the end of the 
chassis to receive the 12V from the car 
battery. Once these terminals are in place, 
the power supply parts can be fitted under 
the chassis and wired before building the 
rest of the rig. 

It is best to get the power supply 
working before proceeding with the rest of 



the wiring. All parts were mounted using 
lock washers and then dabbed with Glyptal 
varnish to keep the nuts and bolts from 
vibrating on bumpy roads. The rig was also 
mounted on load mounts to help absorb 
some of the shock since this rig was 
intended to stay mounted in the car. 

The oscillator plug-in coil forms were 
snagged from a plastic sack hanging in the 
radio store listed as "Calectrocorp, low-loss 
plastic coil forms, Cat, 1-899P." The sack 
with a socket and coil form was listed as 
1-898-A. It took 30 turns of 28 AWG 
enamel for the 80m coil, 19 turns for 40m 
and 9 turns for 20m. The coils are terrific, 
they plug in and out easily, and the base 
will unscrew to make wiring into the 
prongs easier. The pi-network coil was 16 
turns per inch, \ X A in. diameter No, 1416 
\ir-Dux bulk coil. If your local parts store 
doesn't have it, it can be obtained from 
Western Radio, India St*, San Diego, 
California. 

Tuning 

In most instances, neutralizing was not 
found necessary with the 12DQ6 tube; 
however, the circuitry was included. A wire 
was soldered to the bottom of the oscil- 
lator coil and the junction of the 270 pF 
capacitor to a feedthrough insulator. On 
the top side, 4 in. of 18-gage wire was 
soldered vertically alongside the tube, To 
neutralize, turn on the oscillator and 
remove both the plate and screen voltage 







MAY 1970 



109 



. 



from the I2DQ6 by unsoldering the wires. 
Pick up the feedthrough voltage in the 
plate tank circuit with a grid-dipper in 
diode position. Now push the vertical 
neutralizing wire back or cut off in small 
nips until the feedthrough voltage reaches 
the minimum possible. The tank should be 
connected to a 5 0O noninductive resistor 
and peaked for 40m during this procedure 

by using the grid-dipper as an indicator. 

Generally the best way to adjust the 
transmitter is to first feed it into a dummy 
load made up from noninductive resistors. 
Once tuned to this 50^2 output, the trans- 
mitter knobs are left almost untouched, 
and the output coax run to the coil. The 
braid is fastened to ground at the same 
place the coil is grounded and the tap 



moved back and forth, adjusting for 
maximum radiation. Closing the trunk 
door will have some effect on the antenna 
adjustment, and if possible tune with the 
door closed. 

Battery Cable 

A long length of 1 2 -gage rubber-covered 
wire was used to go from the trunk to the 
battery. I drilled a hole in the trunk and 
fastened the wire with plastic clamps on 
the body frame to a terminal strip in the 
engine compartment, A 12 V relay was used 
to operate from a toggle mounted on the 
dashboard for turning on the power; how- 
ever, if you can run the wire inside the car, 
a good heavy duty 1 5 A switch will suffice, 

. . . W6BLZ ■ 



5 T NOfflEN ON 
4? OHM RES l W 



Aifl DUX NO 1416 

80 M 30 T Z0U9T 

00^ 40 M 19 T 

2KV 




-I2VDC 
N£G 



cot 

BOTTOM OF 2N1358 



f>0$ 

12V CAR BATTERY 



Fig, 1. Schematic. 



110 



73 MAGAZINE 



(continued from page 13) 

business mail like this. Little of this really has to 
be done on paper or to be physically sent in an 
envelope. 

Picture a small typewriter with a"built-in tape 
recorder. IBM has just such an item that we use 
for typesetting, so there is nothing basic; left to 
be invented, just compromises to be made for 
mass production and cost-cutting. For not a lot 
more than the regular phone service a unit such 
as this could be rented and connected to the 
phone lines. All businesses have phones, and all 
but a few homes have them* so a service using 
this existing facility would get just aboui every- 
where. 

Your tape-typer would correct mistakes 
merely by back spacing and retyping over. 
Instead of paper it could print out on a small 
television screen, When the message is 'Completed 
it could be addressed to a phone number and, 
with the push of a button, sent on its way. You 
want a copy? Another button would put it on a 
permanent tape for your file, coded for fast 
retrieval. 

The phone would not be tied up with this 
system since it could operate while the phone is 
being used normally. 

The phone lines are already all in, so all that 
would be needed for this system would be the 
tape-typers and the automatic routing equipment 
in the phone company exchanges. 

The cost per message should be a fraction 
of the present cost of sending letters. And think 
of the saving in paper, stamps, typewriters, 
ribbons, and shoe leather for the postmen, Even 
at that, the mailmen won't be out of business by 
any means, for they will still have to struggle 
through the sleet and hail to bring you magazines 
and ads for Florida property. 

Incoming messages would be taped and could 
be read art your leisure. Permanent copies can be 
made of important messages on tape cassettes* 

If we can reduce the mail load by 80% 

perhaps they will be able to get the magazines 

through in better time? And wouldn't it be nice 

to be able to send letters again for 24 and have 

them delivered within seconds of being sent? 

That would be better than the old two deliveries 

a day we used to have a few years back. 

73, 

• . . W2NSD ■ 




. i 



Not that kind, dummy!" 



you find radio exciting . 

you like "projects" . . . 
. you're curious about 

ham radio . 
THEN YOU'LL DIG 73 













73 sells on the newsstand for $1 
per copy, but you can get it for 
a fraction of that price . . . and 
delivered right to your door! 

SUBSCRIBE WOW - 
you'll never find a better time. 

Take advantage of 
the special M sale: 

1 year $6 

2 years $11.99 

3 years $12.00 



encli 



Name 



Address 



l 
I 

I 
I 

IJiilTii 



Call 



City /State/Zip 



73 MAGAZINE 
PETERBOROUGH NH 0345C 



iJ 






MAY 1970 



111 






Pat Cabell W A? EMM 
79 Newcomer Road 
Richland WA 99352 



A little FM unit that should be 

available in two surplus 
markets — commercial & military 





Now that you have read all the fine 
articles in 73 Magazine about the fun 
of FM, let's talk a bit about the kind of 
mobile gear you are going to get. This surely 
deserves a lot of talk, for there are some 
surprises in store for the unwary. 

You hear about a fine piece of gear made 
by Motorola or GE, and you take a look 
— and you generally see a monstrous con* 
traption too big to get into the seat or the 
trunk of a small car - with enough tubes in 
it to stock an electronics distributor for 
life — and a circuit so complicated that some 
of us have been known to faint dead away at 
the idea of even taking off the cover! Maybe 
you like vast puzzles — but some of us don't. 

So you try for a little one: a "handle 
talkie'' sounds like a great idea — and in 
some ways it .is. Take one of the older 
low-priced models: Has just a little power - 
has a headset like a telephone that gets very 
tiring to hang on to — has a small number of 
tubes, but they are in some cases so old and 
rare that you will have better luck searching 



for spares in the Egyptian pyramids than in 
your electronics catalog. And if you want to 
go ac powered you have some rare and 
refreshing problems in rigging up a power 
supply to handle your antique curiosity. 

There are some modern, compact FM 
transceivers, and I won't knock them at 
all - they do a real great job - particularly 
when you realize that with a repeater you 
only need about one watt output to have a 
tremendous signal on the band. 

But if you are like me and don't have a 
lot of spare cash lying around, then you will 
want to look at something a little lower 
priced. So, how would you like to get a 
small, compact transceiver — with power up 
to SOW out; that is neat, dependable, re- 
liable - that's proved itself throughout the 
world for maybe 25 years, that's used in all 
types of state and federal aircraft and at 
airports, that is a proved performer in Coast 
Guard service, that did a bang-up job at the 
South Pole in Operation Deepfreeze, and 
that in rugged service in Alaska stood up 



112 



73 MAGAZINE 







better than far more complex and sophisti- 
cated units? How would you like a trans- 
ceiver that is old and moderately priced, but 
with tubes that you can still find in the 1970 
Allied catalog? And how about a unit with 
absolutely no trick circuits, with plain, 
conservative, simple design and layout for 
easy maintenance, a unit so simple in fact 
that this old horseracing writer can, with his 
feeble knowledge of electronics, part ml ly 
understand the thing in at least a dim and 
groping way? 

We are talking about the equipment made 
by Combo, in Coral Gables, Florida, And we 
are talking about their old tube-type equip- 
ment. (They, of course, now put out a 
modem line of solid state gear at the usual 
industrial price levels, but we are not talking 
about that!) My own set is an old Model 
275, which was made some time before 
1950. I paid the huge sum of $10 for it, It 
still puts out a tremendous signal — I0W out 
(in commercial practice they use watts out 
to measure power — 10W out is equal to 
maybe 20W input). 

No, I don't own any stock in Comco. Nor 
do I have any of their gear to sell (Fact is, 
my only contact was when I wrote for 
information on the Model 275 - I got a 
prompt answer, but no information!) 

We will talk mostly about the Model 582. 
This is a good rig, and represents the kind of 
equipment they made in the past. There are 
lots and lots of other units they make that 
are suitable for amateur service — I have 
listed them in B, Table L There is my Model 
275, with a single channel, a 6V mobile unit. 
It's a handy 2 meter rig, Model 580 is good 
for the 6 meter band it can have all kinds 



of power supplies and may have one or two 
channels, and an output of 25— 50W. Model 
680 is for the 6 meter band, and can run I 
to 4 channels with up to 100W out, A lot of 
power there. Model 906 is a somewhat 
advanced piece of gear that would also be 
very fine on the 6 meter band; 

For the 2 meter band, we have Model 
582 f which gives you one to two channels, 
and 18-25W out. Model 682, another fine 2 
meter rig, will get you up to four channels 
and 75 W out. Model 800 is a sophisticated 
hand-held transceiver of the modern genera- 
tion, and Model 900 is a modern transis- 
torized portable rig - both are great on 2 
meters. Also for 2 meters there is quite a 
range of military equipment (Table II). 
These have a bewildering variety of power 
supplies to meet military needs! The 
AN/FRC-70 and 70A run 50W on 2 meters, 
the AN/VRC Models 42, 51, 5 IX, and 52 
run 25 W on 2 meters. These are dandy rigs, 
and require no appreciable retiming for use 
at 144-148 MHz. The AN/VRC-58 is 
another excellent 2 meter rig. 

Some of the military rigs will hit 10 
meters with little trouble. The AN/FRC 
Models 52, 52A, and 52B will give 50-60W 
out. The AN/VRC 33 and 33A are single- 
channel mobile units (at 35W out) and won 
fame in Project Deepfreeze. And, for 10 
meters, the AN/VRC-60 works great with a 
12V power supply and gives out a good 
25W, 

Or maybe you would like to try the 
popular amateur UHF region (called 450 by 
FM'ers). Try Model 684 shown in Table I; 
you get 10 to 25 W out in the 450 MHz range 
with no tuning problems. 






:f 



-_ 




Fig, L The Mode! 582 For mobile mounting. 



MAY 1970 



113 




lONITfcON SWITCH 
(OPTIONAL FT* fUflt! 



HOl-f IMO- 

CO"iT«Ot - FO»EI? SUPPLT 

SP["I* CASE 



* Fig. 2. Mobile hookup for the Model 582, 



Let's look at some pictures. Figure 1 
shows the 582 set up for mobile mounting. 
The little case, about the size of three reams 
of typewriter paper, will fit anyplace. The 
control head, speaker, and mike go under 
the dash. Figure 2 shows the mobile setup. 



upstairs. Or, with some of the beatup, 
cobweb-covered battle-scarred veterans of 
other wars you find in surplus stores, it is 
best to dig a hole and give the whole thing a 
burial rather than to clutter up the living 
room or study with it. 





Fig. 3. Model 580/582 hand-held portable rig 
with an output up to SOW. 

Figure 3 shows the 582 made up in a battery 
powered hand -held rig. This is no. toy trans- 
ceiver — it's got a good speaker and good 
mike — and a solid 50W output! It has an 
ac/dc power supply, is just about the handi- 
est rig you could get hold of. 

Now let's talk about the base setups. On 
some of those big, black rigs we mentioned 
earlier, you will use up half a room to store 
it and get some unhappy looks from the 
XYL if you even think of bringing it 



Fig. 4. The Model 582 makes an elegant base 
station. 

But we don't have these troubles with the 
582. Figure 4 shows how it makes an elegant 
base station, suitable for just about any 
room in the house. 

Now, let's sort of flit through the block 
diagram in Fig. 5. The transmitter section 
multiplies 1 6 times for 144 MHz output and 
will take crystals in the 9 MHz range. 
Starting at the front, we have the oscillator 
feeding into the "phase modulator" tube. 
Don't let that term "phase modulator" scare 



114 



73 MAGAZINE 




OSCILLATOR 



X 



PHASE 
MODULATOR 



2X OR 
3X 



2X 



2X 



2X 



V-ZGI 
6AK6 



V-202 
6BH6 



V-203 
6BM6 



V-2Q4 
6BHS 



V-205 
6AKG 



V-2Q6 
7558 



V-207 
6146 



M<t 
INPUT 



V 2Q8A 
I2AK7 



tf-209 
6AL5 




V208A 

1/2 
I2AX7 



• 1ST 
MULT 


2ND 3RD 4TM 
MULT MULT MULT 


FINAL 


. . 


144 MHz- {2KK2XK2XM2X)- i6x 
174 MHz* (3XNJXH2XH2X)- 24 X 





1ST 
SPEECH 

AMPL 



CLIPPER 



2ND 
SPEECH 

AMPL 




V 5 
68H6 



250 KHi 
I-F 2 



2ND 
MIX 



V-4A 
(2AT7 



2ND 
LlMlTER 



1ST 
Li MITER 




2ND 
IF2 
AMPL 



1ST 
I F2 

AMPL 



V 12 
6BHE 
NOISE 

AMPL 




B 550 



X 

T 






V-3 
6BH6 



BBMHj 
l-F t 



V 2A 
12AT7 



IF 
AMPL 



1ST 



V-*B 
12 AT 7 



1^ — 
2ND 

DSC 



4x 



v 2B 

I2AT7 



MULT 



AUDIO AMPL 



AUDIO OUT 



TO SQUELCH 



3RD OVERTONE FREQUENCY CRYSTAL - 34 MH| 
DISCRIMINATOR 



AUDfO OUT 



Fig. 5. Block diagram, typical 144—1 74 mc transmitter-receiver, 582 type. 



ANT 
RELAY 



t 



VI 
6AK5 

"rf" 

AMPL 



V I4A 
I2AT7 



OSC 



TO 
ANT 



x 






you. AH it means is that we are modulating 
after the oscillator, instead of at the oscil- 
lator. This allows a wider flexibility in 
control of "deviation*' (Modulation) and is 
otherwise undetectable from frequency 
modulation per se. 

How the thing works is not im- 
portant — and I don't believe half the stuff I 
read about how the electrons gallop around 
anyhow —but it is important to know thai 
any variation on the plate voltage of the 
modulator tube will modulate the signal, 
whether you want it modulated or not! So 
keep a sharp lookout for loose connections, 
intermittent shorts in capacitors, and the 

like. 

From then on you multiply out all the 

way. One big advantage of FM (we call it 
that, anyway) is that any of the signals 
getting out—such as the lower har- 
monics—will be less likely to tear up your 
neighbor's TV reception. I have a friend who 
had nothing but neighbor trouble with a 
flea-power AM outfit, then he switched to a 
30W FM outfit and there has been nothing 
but joy in the neighborhood since. By the 
way, he has demonstrated that he can take 
his 2 meter FM gear and trip our local AM 
repeater, and I can hear him great on my AM 
"Twoer"— guys with sets not a megahertz 
wide in front can copy him easily, too. 

Now let's see what we can do with the 
receiver. The stuff comes in at, say, 144 



MHz, and there is a stage of rf amplification- 
Then you have to convert it to the first i-f of 
8,8 MHz. That works out to about 34 MHz 
in the oscillator, multiplies four times to 
about 136, and there we are. Only there 
ain't no crystal which we can afford at 34 
MHz, so we buy a third overtone crystal and 
weVe in business. 

Then we have an 8.8 MHz i-f amplifier 
and another mixer. We feed the mixer with 

4 

an 8,550 MHz signal from our crystal oscil- 
lator, and here we are at the second i-f of 
250 kHz. That makes for nice selectivity. We 
run that through two amplification stages. 

Now we hit two "limiter" stages. The 
idea here is to remove any AM components 
(such as noise) from the FM signal. The 
limiter chops off any high peaks and the 
whole thing comes out at a constant level. 

Now the discriminator looms up before 
us. This is simply the same kind of a 
function as the "detector" gives us in an AM 
set. Next comes an amplifier and squelch 
circuit, designed to make life easier for the 
listener. 

That's about all there is to it. And it's 
why I say that the best buy in mobile FM 
gear is surely the .Comco Model 582 or one 
of its brothers. Many, many thousands of 
such FM models have been made — you 
should be able to locate one without too 
much trouble. Good luck! 

. . , WA7EMM" 






MAY 1970 



115 




SCIENCE 

EDUCATION? 



by Fred Mocking 
Science Editor 
Radio Today 



Every year, many of our grammar 
schools and high schools participate in 
"science fair" programs. The purpose of 
these fairs is to stimulate interest in science 
and to provide experience in working on 
science projects. Students who enter the 
fair do indeed gain worthwhile experience 
and knowledge. Many of them are fortu- 
nate in having guidance and help from 
parents with technical skills, or help from 
parents or other adults with access to 
unusual technical facilities. Although 
science fair regulations attempt to rule out 
this type of help, the students do, never- 
theless, benefit from it. Indeed, if they 
were to depend solely on their own 
resources, many students would be unable 
to enter projects at alL 

In spite of the positive values present in 
science fair activities, many thoughtful 
observers have questioned the basic 
premise that science fairs stimulate interest 
in science. This may astound those who 
have visited these fairs and who have seen 
the truly outstanding accomplishments of 
our youngsters. Yet the skeptics state that 



the students who receive the maximum 
encouragement and assistance are those 
who have the greatest interest and ability 
in science and thus who are least in need of 
help. Without doubt, science fairs help 
them, but what about the rest of the 
students? Are they better off, worse off. or 
unaffected by the fair? 

Another question that has been raised, 
and moreover that has been raised by 
student entrants and by student winners is 
the fact that the "spectacular, flashy 17 
exhibit wins. Many students believe that 
this is so and thus deliberately choose a 
project, not on the basis of their own 
interest or the intrinsic value of the pro- 
ject, but on its potential ability to impress 
the judges. As a consequence, we have 
students who will enter a laser or a Tesla 
coil exhibit while at the same time having 
no conception at all of the more elemen- 
tary principles involved in electrical cir- 
cuits. Thus, superficiality is encouraged at 
the expense of a firm understanding of 
basic principles. Is it not surprising that 
activities sponsored by educational institu- 



116 



73 MAGAZINE 












tions should drift so far from sound educa- 
tional principles? 

A closer look at the science fair itself 

will provide some insight into this state of 
affairs. The primary object ive of most 
students who enter is to win! Those who 
progress through the local, district, and 
state fairs may win one of the valuable 
scholarships offered and, after gradual inn 
from college, many are offered jobs by 
leading technical companies. In other 
words, the science fair program provides a 
simple, straightforward technique for 
"skimming the cream" of the scientifically 
able students and steering them into the 
technical fields that are vital to our 
national progress. 

Now, I have no quarrel whatever with 
people who "skim off the cream" but I 
cannot accept this as a process that results 
in "enriching the milk." Our nation has a 
vital need for people in many fields who 
have sound backgrounds in science and we 
cannot afford the luxury of haphazard 
dependence on the relatively small group 
whose interests happen to lie in the science 
area. 

A number of educators have become 
dissatisfied with science fairs for this and 
other reasons and have discontinued 
science fair activities in their schools. Other 
educators simply have a vague feeling that 
something is wrong without being able to 
identify it more specifically. 

If we are to improve this situation, let 
us accept as a basic premise that some of 
the science fair activities should result in 
some positive return to the schools 
involved, that is, some benefit for all the 
students, and perhaps even for the teach- 
ers, who put forth so much effort towards 
making these fairs successful. This could 
lead to the following guides for new 
categories of science fair activities: 

JL Science fair activities should, in part, 
result in equipment that may be used 
in the schools, and be relevant to the 
existing science curriculum. (Few 
teachers would complain that they 
already have too much equipment.) 

2. Reduce the emphasis on original 
research by providing for projects 



based on hardware that simply and 
effectively demonstrates known prin* 
ciples incorporating student "feed- 
back." This area has hardly been 
touched and in itself offers many 
opportunities for creative work. 

3. Encourage projects that lead to 
simple experimental equipment that 
can be duplicated in classroom quan- 
tities in the school shops. Thus school 
laboratories can acquire equipment 
for each child rather than a single 
demonstration apparatus for the 
entire classroom. 

4. Eliminate the need for concealing or 
apologizing for parental aid. If the 
student can bring to bear unusual 
resources in technical aid and equip- 
ment for the benefit of the school, 
why rule it out? 

Other rules may be suggested, but the 
four items above are sufficient to show 
what the potentialities of science fair acti- 
vities may be, once we choose our objec- 
tives properly. 

Schools have been criticized for a lack 
of contact with important new concepts in 
technology and science. This problem is 
not the fault of educators* it * s the result of 
a total lack of two-way communication 
between educators and the scientists and 
engineers who are familiar with current 
technology. Hem 4, listed above, can be 
used to provide one framework for such 
communication by means of projects based 
on the very technology and devices that 
the schools would otherwise be unable to 
obtain. Anyone familiar with modern 
industry realizes that creation of a sound 
design takes considerable time and effort, 
but once such a design is created, it can be 
readily duplicated and made available for 
many users. Why should such a basic 
economic fact of life be excluded from our 
educational institutions? 

Science has given us techniques to 
achieve almost any technological goal we 
may care to establish. It is time that we 
rethink our objectives in science education 
and write rules thut will get us to our goals. 
To do any less is, to say the least. 
unscientific. ■ 






MAY 1970 



117 



. 




Tied in with the local repeater, this phone patch 
received approval from Ma Bell . . . 



The purpose of this article is to give a 
description of the automatic telephone 
patch system developed for the two 
Wichita 2 meter repeaters. The features 
include mobile dial control, giving the 
mobile radio amateur access to the landline 
telephone system, as well as making other 
functions available to him* Many methods 
of remote control have been developed; 
most use one or more tones transmitted 
simultaneously or sequentially, but the 
method used at Wichita is a modified 
"Secode" type, or interrupted "single 
tone/' 

Secode systems transmit a tone of fixed 
frequency, interrupting the tone with no- 
tone pulses, created by the contacts of a 
standard rotary telephone dial, The 
decoding units sense the presence of tone 
and count number of "holes/ 5 When the 
proper sequence of pulses (holes) are 
received, the decoder unit will make a set 



of contacts for a short period (momentary 
"make"). A single decoder unit can be set 
to select from one to five functions at the 
remote location. We use separate functions 
to turn the telephone patch on and off. 

The Encoder 

The diagrams shown in Figs, 1 and 2 are 
almost self-explanatory. The output link is 
wound on the 88 mH toroid, using as many 
turns as needed. (See Fig. 3.) For high- 
impedance microphone circuits, 10 — 15 
will be required; for low-impedance micro- 
phone circuits, 30 turns should be about 
right. The dial can be almost any type, but 
must have a set of open contacts that 
"make" when the dial is rotated "off- 
normal/' I personally prefer the Strom- 
berg-Carlson dial, which has extra contacts 
and is indicated in the drawings. To use the 
more conventional Western Electric or 
Kellogg dials, the two diodes make a simple 



118 



73 MAGAZINE 




i5oa 




Kl-15 Kl-16 

I L. 



IKE Hi 

* MfKE LO 



TO TIMER 
CIRCUIT 



OFF -NORMAL POINTS 



-J PULSE POINTS 



Fig, J, Schematic showing output portion of dial 
encoder. 



OSCILLATOR 

m 



TIMER 




86 fliH 

TOROlD 2QQ h f Z 



OUTPUT- 
SEE FIG I 



DEPENDS ON 
FREOi 015-04 
FOR 2602^ 



ALTERNATE 
HOOKUP FOR 
WE AND 
KELLOGG 
DIALS 





OFF-NORMAL 
POINTS 



Fig. 2, Schematic showing oscillator and timer 
portions of tone encoder. 



"and" circuit. Note: the dials from ^Trim- 
line" telephones are small and pretty, but 
they do not have the "off -normal" points 
and cannot be used. The dial pulses must 
have the correct speed and make— break 
ratio. Checking dial speed and make-break 
ratio is not difficult; one of the easiest 
ways is a 15 ips tape recorder with editing 
facilities. First, make a recording of WWV 
and the time ticks. At 15 ips the time ticks 
should be spaced 15 in. apart. This verifies 
your tape speed. Next, record the output 
of your tone encoder transmitting the digit 
"zero." Careful use of a grease pencil or 
nylon point pen to mark the on and off 
spaces will show you the speed of the^dial 
and the make— break ratio, in our area, we 
require 10 pulses per second, and the open 
or "break" time should be 60% t In other 
words, ten pulses should take 15 in. and of 



the 1V4 in*, the pulse points on the dial 
should be open about 9/10 in. 

Once you have one or more encoders 
checked out, transmit the tone through the 
decoder to test the pulsing relay. Adjust 
spring tensions, air gaps, and residual 
screws as necessary to obtain the same 
make— break ratio as transmitted by the 
encoder. The timer circuit holds the trans- 
mitter energized during the "interdigit" 
time. The 200 juF value is nominal, and can 
be varied. The relay shown in the diagram 
is a common item, but not critical. To hold 
the tone frequency to ±5 Hz, use of Mylar 
capacitors is recommended. 

The Decoder 

The equipment used in the channel A 
repeater (146.34 to 146.94 MHz, W0DKU) 
is a modified Secode RPD-612 with ac 
power supply (Fig. 4). At first, we used a 
single five-function selector, , model 
49HS-5, We later added a model 70 selec- 
tor with a five-function kit added. We now 
have ten functions we can select and know 
of no reason why more selectors could not 
be added. An additional stage (Fig. 5) is 
"tapped in" at the transformer lead feeding 
the neon bulb. This additional stage con- 
sists of one NE-48 lamp, a pair of diodes, 
capacitors, resistors, a tube, and a relay 
with a set of normally closed contacts. This 
set of contacts is used to pulse the tele- 
phone network and should be tested and 
adjusted to give the 60% break when used 
with the encoder in the "tone burst" 
mode. The relay we used was salvaged from 
junk telephone relays at the local surplus 
emporium. Note that this relay operates 



BB mH TORPIDS 



START 2 




FINISH Z 



FINISH I 



Fig. 3. Sketch shows construction of 88 mH 
toroids. Connect start 1 and finish 2 together (or 
start 2 and finish 1); this gives center tap. 









MAY 1970 



119 



TO ADDED STAGE 




Fig. 4. RPD-612 schematic, digital decoder type 1859. 



(the contacts open) any and every time 
that tone is transmitted to the decoder. 
Also note that due to the difference of 
tone on and tone off times in the two 
modes of encoder operation, the stepper 
unit in the selector will not operate when 
"tone burst" is being used* 

The equipment used in the channel B 
repeater (146.22 to 146.82 MHz, operated 
by Don Pryor, W0IPB) uses the same 
principles but consists of a modified 
RPD-650 Secode decoder (transistors and 
mechanical selector). The Sehmitt trigger 
stage collector load resistor (R22), 4.7K, 
was replaced by a relay, and the emitter 

resistor was reduced in value from 180O to 
100£2. Since the Sehmitt trigger transistor 
(Q5) is normally conducting with no input 
signal, we used normally open contacts for 
our pulsing relay. The model 70 selector 
was modified by adding the five-function 
kit and the operation is the same as the 
other repeater. 

Some "tinkering" was necessary to 
adjust spring tensions in the selector. This 
tightened the tolerance on the make— break 
ratio to prevent stepper action during 
"tone burst." In the RPD-612, the sensing 



of the make -break ratio is in the elec- 
tronic circuitry. In the RPD-650 and 
RPD-650 A, the spring tensions of the 
model 70 selector must be altered to 
obtain this effect. (The RPD-650 and 
RPD-650A are made to operate with 
75-25 or 25-75 make -break ratio and all 
variations in between.) 



01 



i 









IUPU1 FROM 
RPD-612 



NE 49 



i£AT7 

Ofl 
'2AU7 



DIODES USED WERE 
OE-509 SILICON RECTIFIER 




-5> 



PULSING 

^ELAV 

-^ J 



Fig. 5. Secode unit is "customized' for the 

Wichita repeaters by adding a separate stage for 
dial pulsing of the phone line. 



The Telephone Patch 

The first reaction of radio amateurs 
when they see the circuit diagram (Fig. 6) 
is usually "where is your hybrid balance 
adjustment?" Quite simple, since the patch 



120 



73 MAGAZINE 






doesn't use hybrid circuitry and is not 
intended for simultaneous duplex oper- 
ation. Since any repeater must have some 
type of carrier-operated switch, we use the 
carrier switch to change from transmit to 
receive. This has a "bonus" — if the radio 
amateur wishes to interrupt the person on 
the landline, he simply pushes his micro- 
phone button and the landline is no longer 
transmitting. Very useful to prevent out- 
bursts of unbecoming language from being 
transmitted. After all, how many two- 
meter mobiles are equipped for simul- 
taneous duplex operation? 



Ill REPEAT COIL 



TELEPHONE 
LtNE AUDIO 

(man 



OFF -HOCK 
AND 

DIAL. 




TO TRANSMITTER 
MODULATION 
GROUND 

TO TRANSMITTER 
fcrtOOULATiOM 
JNPUT(eoOn) 

TO RECEIVER 

AUDIO OUTPUT 

(GOOll) 

TO TRANSMITTER 
*ETINS ClRCUJT 



PATCH -ON 
-^(MOMENTARY 

MAKE TO GROUND) 



TO TONE 
DECODER 



PULSING 
RELAY 

PATCH -ON 
RELAY 



PATCH-OFF 
RELAY 



ALL RELAYS SHOWN 
DEENERGtZED 



» Z4VDC 

TO COI* 

(GROUND #HEN 
CARRIER Pfif SCNTJ 

PATCH -OFF 
•■{MOMENTARY 
MAKE TOGROUNO) 



Fig. 6. Schematic diagram of Wichita autopatch 
radio/telephone interface. 



An examination of the schematic dia- 
gram shows a pulsing relay, a switching 
relay, the patch-on relay and the patch-off 
relay, plus the call-length timer. The 
pulsing relay is controlled by the presence 
or absence of tone. The points are closed 
unless tone is received by the decoder. The 
call-length timer, a motor-driven unit, 
opens a set of normally closed points after 
a preset time interval. The timer begins 
operation when the patch-on relay is oper- 
ated; it is returned to zero when the 
patch-on relay is deenergized. The patch-on 
relay is held on by a set of points on its 
own point stack* In the event of power 
failure the patch-on relay drops out and 
releases the telephone line. The call-length 






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How to Build and Tune Antennas 

Work more DX with The right antenna for your location. New book 
give* *iep by ■step inttfucttons (176 pages. 200 illustrations) lot building 
every type of antenna long wires, dipoies, yag>s, trap, etc\ Plus many 
other* not described elsewhere: low cost miniature beams from 
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MAY 1970 



121 



timer and the patch-off relay momentarily 
interrupt the power to the patchon relay, 
again deenergizing the relay. The switching 
relay is operated by the carrier-operated 
relay in the receiver. 

When no carrier is coming into the 
repeater, one set of contacts holds the 
transmitter keyed on while a second set of 
contacts connects the audio from the 
telephone line to the transmitter. A trans- 
mission by a mobile unit operates the 
carrier-operated relay in the repeater, 
which in turn operates the switching relay 
in the patch. When the switching relay 
operates, the telephone line is switched 
from the transmitter input to the receiver 
output. The contacts used to hold the 
transmitter on are opened and allow the 
telephone patch to be used in two ways. 

If the patch-on relay is wired to disable 
the normal repeater keying circuit, the 
telephone patch operates in a semiprivate 
mode, The conversation from the tele- 
phone to the mobile goes out on the 
channel, but when the mobile transmits, 
the repeater transmitter goes off the air 
(not shown on the diagram). The way we 
normally use the patch, the carrier- 
operated relay keys the transmitter in the 
normal way and both sides of the tele- 
phone conversation are transmitted over 
the repeater channel Since the "pulsing 
relay*' is open at any time tone is being 
transmitted, practically no tone is ever 
transmitted over the telephone line. 

Both the channel A and channel B 
repeaters are General Electric Progress Line 
repeaters, and are equipped for 600H 
audio input and output. Our phone patch 
transformer is a salvaged telephone 
company one-to-one repeat coil obtained 
from the local surplus emporium. 

System Levels 

Overall system performance will depend 
on how carefully everything is set up in the 
first place. The Wichita repeaters are both 
wideband, We limit audio levels to 12 kHz 
for the mobile units. By setting the trans- 
mitted tone levels to 9—10 kHz, we do not 
have chopping to contend with, and the 
decoders work reliably even when the voice 
audio is just barely understandable. In 



most cases, the audio becomes too poor for 
phone patch quality before the decoder 
reliability enters the picture. Keep in mind 
that hard limiting or volume compression 
will degrade the performance of the 
decoders- It is extremely helpful if a signal 
generator with external FM capability is 
available for testing the system* We have 
verified that the system is erratic at the 5 
kHz deviation level, and is very reliable at 
any deviation level above 6.5 kHz. 

2805 Hz filter 

We retransmit the tone through the 
repeater as we plan to locate muted moni- 
tor receivers in various locations to alert 
needed persons in emergencies. Regular 
listeners who do not like to hear the tone 
can use simple filters such as the one 
shown in Fig. 7 to virtually eliminate the 



68 mH TOROiO 



50K 




APPRO* 
039 M F 



WICHITA AUTOPATCH 
"2805 FILTER* 



Fig. 7. Toroids can be used as 2805 Hz fitters to 

remove unwanted tone signals from receivers. 



tone. Insertion loss is less than 3,0 dB ? with 
tone attenuation well over 20 dB. We use 
two of the filters — one at the input to the 
first audio amplifier stage, and one at the 
input to the second audio amplifier stage. 
We use the 88 mH toroids tuned to 2805 
Hz with a capacitor and a balance potenti- 
ometer, Adjust the potentiometer for the 
deepest null while checking that the fre- 
quency is correct by slight variation of 
your audio generator frequency. Replace 
the potentiometer with a fixed resistor and 
install in your receiver. Possibly higher- or 
lower-inductance coils would work better — 
we haven't tried since these are satis- 
factory. 

Negotiating Permission to Interconnect 

This system requires a telephone line or 
interface at the repeater site. (In the case 



t22 



73 MAGAZINE 




Southwestern Bell Telephone Company 






1*4 N. ■■(wri>*v 






a?. 1969 



Clenan L. Sawyer 

Civil Da fan** Ft*dla Offiaar 

tfiehlt4 - 9*4cwlek County Civil Baft 

2113 $*Uju 

VIehtt*. Eanaaa 6?203 



Cli 



In m#w«r to your l*tt*r of NoTaaa&ar 10, t#* btv* r«c*iT#d approval to 
provide the automatic radio- talephon* interconnect. This irrtngoMnt 
ij allowable If wt provide a etandard lutonatlc Connactin^ Dixit and if 
th* network a,dO*u line la the rotary dial type. 



Va do not have a tariff filing for tola arrang— nt; however, it can 
be prwided through a Special aaiaahly of Equipaunt rata. Thia rata 
will be 17.25 axHitbly and an inat*il»tttm chart* of #20,00 will mp&Lfi 
Thia ■erriee can be provided within JO daya frcai tba placing of an 
order. 

If I can help in arranging for thia iervioe, pleaae call aw at 
268-1 J/6. 

din car* ly. 



Owrald V. Ewxfc 
3pe<rl*l Rcpz-eatfitatlve 



Fig, 8< Letter from Bell granting permission to 
connect a "foreign attachment" to telephone 
line. Note that Bell provides the interface con- 
nection — for a fee, 



of a split location, it will work at either 
one.) I made verbal and written inquiries, 
but for a long time I received no answers. 
As time dragged on, I made a direct 
connection to the telephone line, expecting 
to goad the telephone company into saying 
yes or no. After several weeks of operation, 
the Sedgwick County Civil Defense Radio 
Officer, Clem Sawyer (K0YER), and I 
mounted a new attack using Civil Defense 
prestige as a lever. It took six weeks to 
obtain the permission we sought (Fig. 8). If 
you wish to connect directly to the tele- 
phone line without the telephone company 
interface equipment, connect the off-hook 
and the telephone audio lines in series, 
connect to LI and L2 inside the telephone 
instrument. 

Summation and Afterthoughts 

Detailed theory of digital pulse encoders 
and decoders is out of place in this article. 
Repeater groups wishing to build similar 
facilities into their repeater should try to 
locate a friend in the two-way radio 
business who services this type of equip- 
ment. Information on setting codes, multi- 
function decoders and simple explanations 
of how the equipment works can be found 
in the instruction books for General 




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MAY 1970 



123 







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BACK ISSUE GUNSMOKE ! 

30, count *em 30, stupendous tremendous 
(more handbooks than magazines) fascinat- 
ing enormous devastating incredibly ener- 
vating back issues of 73 .„„ 

ONLY $5,00 

postpaid worldwide 




Yes. ..yes ...yes... he re is a 
golden opportunity to 
Blow your mind on 30 
back issues of 73. Yoy 
>ond us S5 in negotiable 
securities, cash or check 
and we will send you an 
unbelievable miscellany 
of thirty different (all 
different) back issues, 
all from the 1960-1966 
era. These are all rare 
collectors items. Every 
one could likely be wo- 
rth a fortune to you. Who knows, you might 
even find a rare January 1961 in this pilet We 
don't even know what is in these packages, To 
keep costs down we have had these magazines 
packed into sloppy bundles by the Chimps 
from Benson's Wild Animal Farm {nearbyh 
Watch out for banana skins. —If you want 
specific issues of 73 they are available at the 
low low (high) price of SI each. Unless we 
don't have them, in which case the price is 
higher. —How about sending a bundle to a DX 
friend? Back issues of 73 are worth their weight 
in unicorn dung in most countries* —Money 
received without a shipping address will be used 
for beer, 

73 Magazine Peterborough NH 03458 



Electric EJ-18A,B»C, and D digital tone 
decoders, I all solid-state, no relays) and 
Secode Corporation SD-30 and SD-40 (also 
solid-slate). The General Electric "Data- 
file** has several folders on Secode encoders 



Parts List 

1 - Dial, Stromberg Carlson or equiv,. 

or \V.li. or Kellogg dial, alternate. 
1 88 mil Toroid. w/added winding* 20-50 

turns. 

I - Dpdl Switch 

I - Relay, 4 pdt, allied control 

fr- 154 Series CC-CC, I2V. IKSOCoil 
1 - 1 kO potentiometer (output lever) 
3 - NPN transistors (2N27I2) 
1 - 200 0- 15V capacitor 
1 - .005 JUF Mylar capacitor 

1 - Capacitor, vary to place on 

frcq,, (.035-.O4 for 2805 Hz) 

2 - 47 kQ 
1 - 33 kO 
1 - 680O 

1 ^4700 
1 330^ 

1 - 270S2 

2 - 15012 
1 - 22il 

1 - 10f2 



and decoders. Local sales and service out- 
lets for Secode Corporation can obtain 
information for you regarding single and 
multifunction models of their RPD-673 
( 1 2 V, for mobile use) and RPD-674 ( 1 1 7 V, 
for station use). Similar types of encoders 
and decoders are available from Scantlin, 
among others. Now that a large number of 
Wichita area amateurs are equipping them- 
selves with the necessary encoders, we are 
adding features like selectable loose or 
tight squelch settings, tone key to energize 
the repeater during skip conditions or 
temperature inversions (normally the 
repeaters are to be carrier-energized, but 
during mild band openings things get 
hectic), and many others. We may be 
wiring up more selectors any day now. 
Transient 2 meter mobiles are welcome to 
use our auto patch facilities, but they must 
request the current on and off codes and 
meet the specifications as given in this 
article, 

, . . W0DKU ■ 



124 



73 MAGAZINE 




o 




Mosley beam antenna (TA36-40) on the roof oi 
the Science Museum. Photo from the Science 
Museum t London. 



Bruce Ellison 
San Francisco 
Casas de Binicalaf 
Menorca (Balearic Is!) Spain 




Few hams can boast of a shack about 
35 x 35 feet, two stories high, 
packed with equipment, most of it lent or 
donated, and logging between five and ten 
thousand contacts a year. 

In London, England, though, the Sci- 
ence Museum runs just such a station — 
GB2SM, operating from the second floor 
of the museum's rambling building in 
London *s fashionable Kensington area. 

GB2SM is on the air twice daily —at 
1 1 :30 a.m. and 4 p.m. London time (1030 
and 1500 GMT) demonstrating the princi- 
ples of radio communication to an often- 
eager crowd. 

As the station's QSL cards indicate, 
GB2SM operates with a Mosley T A 36 -40 
beam antenna (on 40. 20, 15, and 10 
meters), and Collins KWM-2 SSB trans- 
ceiver and 30L- 1 (500 watt PEP) linear 
amplifier. Three receivers are in use, and 
their signals can be put out through two 
large ceiling speakers. 








MAY 1970 



125 




Part of the main console of GB2SM t the Science Museum demonstra- 
tion in London. 



The station exchanges more than 3000 
QSL cards annually. 

GB2SM is not strictly an amateur sta- 
tion, as its somewhat unusual call sign 
indicates. Technically, the operation is a 
"demonstration station." Call signs in 
Britain beginning with GB are normally 
reserved for things like radio shows or 
conventions, and then on a temporary 
basis. The museum station is the only one 
in Britain with a permanent GB call. 

Operations were started in August, 
1955, to provide a means of getting young 
people interested in radio communication. 
Many of the more than 2 million annua! 
visitors to the museum are under 21 , and a 
good proportion of these can he found 
standing, fascinated, listening to conversa- 
tion between GB2SM and other parts of 
the world. 

"We know of quite a few young peo- 
ple, 1 * says the museum official in charge of 
the station, "who now hold licenses, and 
who tell us that their interest was first 
awakened here," To which staff operator 
Geoff Voller adds, -"1 worked a man some 



time ago who told me that he'd been 
wailing for a contact with us for years. He 
said he first got interested in ham radio 
here and had wanted the contact ever since 
he got his license." 

Voller, a full-time museum staff 
member, and himself a licensed amateur 
(G3JUL) runs many of the museum's ham 
demonstrations. On weekends, and on holi- 
days and vacations, he is assisted by a small 
group of specially invited British amateurs. 
Because of the "demonstration station" 
status of GB2SM, all use the station call 
sign when operating, never their own call 
letters. 

GB2SM maintains regular contacts with 
several parts of the world; a schedule with 
ZD9BM in lonely Tristan da Cunha is 
probably the most interesting of these. The 
museum station has occasionally proved a 
valuable auxiliary communications link 
during emergencies in Tristan. 

During a recent morning demonstration, 
a contact attempt with ZD9BM was unsuc- 
cessful. In short order, however, the station 
logged QSOs with 9V0PA in Singapore and 






126 



73 MAGAZINE 










with WA8RIS in Cleveland, who was call- 
ing CQ at the time. A brief contact with 
WA0ITW (also CQ), and with OK2PJ in 
Czechoslovakia completed the half-hour 
operation. 

Another morning Volier was "talking" 
with a friend in Holland via teleprinter, a 
form of amateur communication much 
more common in Europe than here. 
GB2SM maintains a teleprinter schedule 
with PE2EVG, a demonstration station in 
Eindhoven, Holland, home of the giant 
Philips electric firm. 

The Science Museum's shack has walls 
covered with awards. The station enters 
about two contests a year, each of which 
requires a high degree of organization and 
logistic support ("we have to make all 
kinds of special arrangements to get people 
into the closed museum at 2 a.m. Sunday 
— that sort of thing - and keep an urn on 
the boil somewhere all weekend/' says one 
museum official). 

The museum's ham operator, Geoff Volier, adjusts 
teleprinter equipment during a contact with ^^ 
PE2EVO, in Eindhoven, Holland. 

Geoff Volier at work on his teleprinter during 
"conversation" with Holland, Note awards on the 
walls. 














MAY 1970 



127 





GB2SM t London, at work. Operator Geoff Voller makes log entries at the conclusion of a half -hour 
demonstration. Station operates at J 030 and 1500 GMT daily, demonstrating principles of radio 
communication for a crowd in the Science Museum, 



Despite the logistics, GB2SM has more 
than its share of awards. It boasts such 
citations as the Keystone award from the 
Harrisburg, Pennsylvania Radio Club, for 
being "the first station in England" to 
work more than 100 hams in Pennsylvania; 
the ARRL DX Century Club award, and 
the League's WAS award. 

The Radio Society of Great Britain has 
given the station its "Empire DX Award" 
for contacts with 50 dominions and coloni- 
al areas on 14 MHz, and 50 additional 
contacts on the remaining bands. 

Although the station can operate with 
code, voice, or teleprinter, most contacts 



are made with voice because they are the 
most meaningful to the ever-present audi- 
ence. 

Amateurs visiting Britain are invited to 
stop in the Science Museum to see the 
station at work. Its operators rarely see in 
person any of their thousands of contacts, 
and are glad of the chance to do so. 

There is one restriction, though. GB2SM 
is not a "public" station, and is not open 
for use by any visiting amateur. You are 
most welcome, but the rule must be 
"please look, but please don't expect to 
operate/" 

. . , Bruce Ellison ■ 



128 



73 MAGAZINE 




Charles J. Vlahos WB2ICV 
1 5 Indian Drive 
Woodcliff Lake NJ 07675 







Hardly an issue of 73 goes by without 
some articles devoted to miniature 

equipment. Test equipment, receivers, and 
even transmitters are rapidly going (he 
miniature route. Smaller and compact rigs 
have much to offer, of course - not only 
in terms of reliability, stability, and instant 
warinup because of solid state design, but 
because they take up less space in the 
shack. 

Yet, for some time I have found an 
irritating fault with miniature equipment. 
Indeed, it even goes (o standard size 
equipment. Call it instead an annoyance, or 
a discomfort. My complaint? Opera ling 
knobs are just loo small to he comfortably 
manipulated with efficiency. 

I much prefer large, massive knobs on 
all my gear whether they be on my 
tube-type receiver and transmitter or on 
that little solid state, homebrew transistor 
checker I often use. So where I can. I 
install knobs to about twice conventional 

size. 

It's true that some manufacturers (like 
llallierafters. National, and Heath) gener- 



ally use large knobs i about 1 in. diameter 
or morel on functions other than the main 
tuning dial, But most don't. Look at the 
new lines of transceivers and you'll see 
what we mean. Mom come equipped with 
tiny, delicate knobs, seemingly designed 
for a feminine touch. 

Fni nol much of a con lest buff, but if I 
were, I could offer a couple of strong 
reasons for large operating knobs. Fox one 
thing, larger knobs would eliminate 
groping, fumbling, or accidental manipula- 
tion i-tl' the wrong function during hectic 
QSOs. For another, they would allow you 
to make critical adjustments with ease (the 
turns ratio would be in your favor). 

Why, then, the trend to small knobs? A 
hasty conclusion might be the limiting 
factor of the equipment's basic size. But 
upon looking over main catalogs ami 
advertisements, you'll find that this jusi 
isn't the case. There is usually more than 
adequate space to double present knob 
M/e So we can conclude that size of rig is 
generally not a factor, 

One valid consideration might be eosl. 
But here anain. a check in the current 






MAY 1970 



129 




Lafayette catalog shows the difference 
between a % in. plastic knob and a 1 in. 
knob of the same material and design to be 
a mere 3tf. Fluted knobs, commonly found 
on most commercial rigs and some well- 
designed homebrew rigs, have a price span 
of 4 to 5^, from the smallest to the largest 
diameters. So the cost differential that 
we're talking about is really negligible. 

On the face of it, then, there appears to 
be no meaningful justification for tiny 
operating knobs. Therefore, if you feel as 
we do, you can modify your present 
equipment with larger knobs at a nominal 
cost. And as for homebrew jobs, there isn't 
any sound reason for going the miniature 
route all the way, 

At this point you're probably thinking 
that this entire business of optimum knob 
size (and shape) is not nearly as important 
and meaningful as Pve indicated. But it 
is - and here's why: 

The space age has ushered in a whole 
new science called "human engineering" 
that deals with this very subject. Believe it 
or not, there are hundreds of engineers 
around the country who devote their entire 
time to such things as scientifically deter- 
mining what size knob, dial, toggle switch, 
lever, pedal, etc., is best, what material and 
color it should be, and where it should be 
best located on a particular piece of equip- 
ment. The findings of human engineering 
have been so revealing to space technolo- 
gists that even industry is beginning to 
take a hard look at these results - all in the 
interest of getting maximum production 
from machines. The whole idea is to make 
manipulation of controls as easy and as 
effortless as possible for humans that have 
to operate machines of any kind. In other 
words, it is a science devoted to lessening 
human fatigue and thus optimizing pro- 
duction. 

The implications of human engineering 
to amateur radio are obvious. The amateur 
fraternity is always striving to improve* 
update, and streamline equipment with a 
view to improving operating conditions. 
The technical articles in the various ham 
magazines attest to this. So it appears that 
knob size is one detail that serious ama- 
teurs should not overlook. 



An important question to ask at this 
point, then, is: What is the best knob size? 

Has human engineering made studies in this 
area? Have conclusions been reached? 

Since an operating knob is basic to 

virtually all electronic gear, one can right- 
fully conclude that studies in this direction 
have, indeed, been made. The findings are 
particularly interesting and support the 
author's view that knobs for amateur gear 
are - in the main - loo small. 

The August 1969 issue of Human 
Factors magazine contained an article by J. 
V, Bradley on "Optimum Knob Diameter." 
Essentially, Mr. Bradley stated that when 
frictional resistance is heavy, the best knob 
diameter is about 2 in. Actually, he 
described a range of diameters (relating 
turning time to knob diameter) for such 
applications to be between \% and 2 in. 
Anything over and under these diameters is 
"significantly inferior." What constitutes 
heavy frictional resistance is something else 
again. But if we were to classify main 
tuning dials on receivers and vfo's as those 
having heavy frictional resistance, then it 
would appear that both homebrew and 
commercial rigs adequately meet these 
specifications. 

But Mr. Bradley's article goes on to say 
that when frictional resistance is reduced 
to a minimum level, specifications change. 
Here, human engineering recommends 
diameters from 1 to 3 ! ^ in, Bradley con- 
cludes by saying that these findings are 
valid over a wide range of rotary inertias. 

It isn't often you see rf gain, audio, 
bandswitching, bfo tuning, or final tuning 
controls that meet this lower tolerance 
limit. At one time, when receivers and 
transmitters came in large packages, they 
did. But nowadays they rarely do, 
especially transceivers. Result: smaller 
knobs and dials. 

The next time you put together a 
homebrew rig of any kind, give some 
serious thought to large knobs iuxd see if 
you don't feel a bit more comfortable with 
them. Or better yet, try installing larger 
knobs on those appliances you have now. 
You'll see what we mean. 

. . . wb:icv« 



130 



73 MAGAZINE 









NEW PRODUCTS 



Low-Cost Function Generator 

Phase Corporation is marketing, as a kit 
or wired and tested, its low-cost solid-state 
test oscillator, which generates square 
waves, pulses, or sawtooth waveforms from 
0.1 Hz to 100 kHz. Portable and compact, 
the package contains FET and unijunction 
circuitry to cover the operating spectrum 
in six continuous ranges. In the kit form, 
which sells for $34.95, all parts are in- 
cluded; transistors, diodes, switches, 
etched and drilled printed-circuit board, 
custom cabinet with screened and punched 




front panel, and easy-to-follow assembly 
instructions. The Model OIK designates the 
kit; 01 W is the completed package, which 
sells for $54.95, (Both prices include post- 
age within the continental United States.) 
Specifications for the Model 01 test oscil- 
lator are as follows: 



Output 
Output Z 



8V p-p, all ranges 
5 kfi 



Sawtooth and pulse: 0.1-100,000 Hz 

Square: 0.05-50,000 Hz 
Risetime 

Square and pulse: 0.5 /isec 
Pulsewidth 

1 /xsec at 100 kHz 

5 msec at 2.5 sec/Hz 

Phase Corp. is located at 31 5 A Boston 
Ave., Medford t Mass. 02155, 



Four-Trace Oscilloscope Preamp 

A four-trace oscilloscope preamplifier, 
the first in a new line of kits, has been 
announced by the Phase Corp. The pre- 
amp is designed for use with any ac or dc 
oscilloscope, providing the capability of 
observing as many as four waveforms 
simultaneously. Individual centering con- 
trol is provided for each of the four 
inputs to the preamp* With an input 
impedance of 1 megohm/channel, the sen- 




sitivity of the preamp is limited only by 
the sensitivity of the scope with which it 
is used. The preamp is compact, facili- 
tating mounting inside the scope housing 
or in an optional case* The circuit of the 
preamplifier employs four FETs and nine 
silicon transistors. Included in the kit is a 
printed circuit board that comes etched 
and drilled. 

Phase Corp., 3 15 A Boston Ave., 
Med ford, Mass, 02155. 

Challenger Beams Are 
Design Innovation 

The Challenger line of antenna systems 

feature w halun-fed, 5-element Tri-Band 
array for operation on 10, 15, and 20 
meters using a single transmission line. It 
has a peak power rating of 1 kW and a 28 
dB front-to-back ratio. 







MAY 1970 



131 



Other Challenger models range from 3/4 
through 80 meters. The entire line, as well 
as other Telrex antenna systems, are des- 
cribed in Catalog PL70 which is obtained 
free by writing to Telrex Labs, Asbury 
Park, M /. 07712. 

Monolithic Synthesizer MOS 

Motorola's MC1125G is a monolithic, 
quad MOS device consisting of four toggle- 
mode flip-flops with buffered Q outputs 
that use no standby power when driving 
capacitively coupled loads. Typical power 
dissipation is a low 75 mW and operation is 
from dc to 1 MHz. The MC1I25G also 







MCA125 



features a typical input capacitance of 2.5 
pF and a crosstalk figure under 1%. The 
MC1125G is recommended for frequency 

synthesis, as required in organ circuits, 
digital dividers, and counters. Motorola 
Semiconductor Products Inc., PO Box 
20912. Phoenix AZ 85036. 

FM Receivers Have 
Built-in Decoder 

Two FM receivers for operation in the 
50 and 144 MHz bands feature a complete 
assortment of optional equipment, in- 
cluding a sequential tone alarm decoding 
facility. The radios are available in four 
model designations. Model TM II-H1 has a 
single-channel, narrowband reception capa- 
bility in the 144-172 MHz band. TM H-Ll 
is the same for operation in the 30-50 
MHz range. List price for both models has 
been set at $115,00, including crystal. 
Models TM 1I-H2 and L2 feature 6-channel 
reception capability in the respective fre- 




quency ranges at list price of $130.00, 
including 1 crystal, (Additional crystals are 
priced at $4.95 each-) 

The receivers are being built as replace- 
ment units for the original TM series. New 
circuitry, however, enables the radios to 
deliver better performance without price 
increase. 

Sensitivity for all models is rated at 0.5 
/iV. Selectivity is set at 50 dB at ±15 kHz. 
The receivers operate on 1 17V with acces- 
sories for 12V dc or internal ni-cad battery 
power supply. Regency, 7900 Pendleton 
Pike, Indianapolis IN 46226. 



Quartz Filter Offers 
Super Selectivity 

Made exclusively for Swan by CF Net- 
works, an all-new 16-poIe quartz filter 
network establishes a dramatic standard of 
comparison. Shape factor of 1.28, ultimate 
rejection greater than 140 dB! A giant 
QRM killer, the SS-16 wipes out strong 
adjacent channel interference with unpre- 
cedented attenuation. And in transmit 




132 



73 MAGAZINE 









mode, unwanted sideband and carrier sup- 
pression are both increased greatly. Avail- 
able only for Swan transceivers, they are 
made for the current 5.5 MHz i-f, or earlier 
5.175 MHz i-f system. Installation and 
adjustment are simple. Specifications are as 
follows: 

• 2.7 kHz bandwidth at 6 dB down. 

• Shape factor 1.28. 

• Ultimate rejection: 140 dB, 

• 16 poles, 16 precision crystals in a 
lattice filter network. 

• Sideband suppression: 80 dB, 

• Carrier suppression: 45 dB with the 
filter alone t plus approximately 40 
dB more from the balanced modula- 
tor. 

• Mounting: Same as standard Swan 
filter, but taller. 

Swan Electronics, 305 Airport Road, 
Oceamide CA 92054, 

Remote-Controlled 8-Position 
Coaxial Switch 

The Series 74 coaxial switch is in- 
tended for use in 5012 circuits at frequen- 
cies up to 2 GHz, where the multiple 
sources are switched to a common out' 
put. To provide maximum isolation, all 
unused terminals of the new switch are 




grounded. In standard configuration with 
type OSM connectors, the switch 
measures 3 in. diameter by approximately 
2 l A in, deep. Other connectors available 
include types BNC ? TNC, 27 series, and 
MB. The switch is normally supplied for 
operation at 26V de. Other voltages avail- 
able are 6, 12, and 120V dc. Dow-Key 
Co., Box 348, Broomfietd CO 80020, 



RF MULTIMETER, RFM-1 




Simplifies construction and testing of solid state 
circuits, antennas and transmission systems. 

-MEASURES- 
1 mv to 100 v DC ±3% 
1 mv to 1 v RF to 1 Ghz ±5% 
VSWR 1.35 and 3.0 fs to 2 Ghz 
to 60 Decibels 

Many more features — Write for detailed brochure 
RADIATION DEVICES CO. 
Box 3450, Baltimore, Maryland 21234 




TRANSCEIVER 

AUTO-MOUNT 

$^95 

* UETAIL 



• Adjiittbli 

• Fits mil noetls 

• Slftiti Imtillatltn 



ARCO MFG. CO. 

P.I. Itl S17, Grind Fwti. H. Oil. 58201 



MAYDAY ! 

urgently wanted 

TOP PRICES FOR: 

AN/SGC-1, 1A Navy Teletype 

Terminals. 
AN/SPA-4A, 4B Navy Radar 
Repeaters. 

Call collect for top offer: 
213-938-3731 

COLUMBIA 





(We have to get rid of these items 
now— 'cause we gotta have the space!) 

CV253/ALR 38-1000 MC TUNEABLE 

CONVERTER 

Excel. Cond Late Model „ $150.00 

COMMAND RECEIVERS 

190 550KC Q-5er Good Condition $14.95 

1.5-3MC Marine Band Exl. Condition $19.95 

3-6MC 75&80 Meters Exl. Condition ,...$14.95 

6-9MC 40 Meters Good Condition $14.95 

COLUMBIA PAYS CASH FAST 

For your surplus military electronic equipment and 

all kinds of lab grade test equipment. Write or call 
collect for top dollar. Highest cash offers in the 
country. We pay all shipping & insurance. Let us 
prove to you what we promise. 

COLUMBIA ELECTRONICS 

apt. 7 4365 W. Pico Blvd.. Los Angeles. Cal. 900 



Dept 



!8£ 



90019 



MAY 1970 



133 



432 MHZ CONVERTER 

MODEL 432CA 

ONLY $64.95 pp. 




JAN EL 

LABORATORIES 



Low Noise Silicon Circuitry* Attractive* Metal 
Ik GrMn STv tino* Built *n 3C Power Supply 
• Silver Plated Cavities • Write for detailed liter 
eture or order direct, specifying if frequency 



P.O. Box 112 + Succasunna, NJ 07B76 
Telephones 20V584-6521 



ALL BAND TRAP ANTENNA ! 





/ 




Redu£» Interference inj « fjj mff OT ALL Amatfttir Tramminin 

rS^** MuV^orlMM. WGu«nWd for 1000 Nam Pow- 

Rr«pr»ori Stronger Complete &. Light, Neat, Weatherproof, 

with 96 ft 72 ohm fcrdline -Scaled rrtonant irapi For novice ttid ill cliu radio 
.matrurV Ellininalei 5 upirate «nitnnas with brtirr perform, mrr guaranicrd 
80-40 20L5 10 meter binds. Complete I Q: fl Sl*95 4Q-:CM S-JG meter bjndt, 
34 ft (bcil far world-wide ihort wave reception l 1 IS. VS. Send only S3 00 (ci|H< 
ck H mo) jnd pay pott mar balance COD plu-S postage fin amvit or send full price for 
posi-pjLij delivery Complete insirui'tjons included 
WESTERN ELECTRONICS Debt A Kctrnev, Nebfwk. 68S4T 



BRIGAR 

ELECTRONICS 

10 ALICE ST. BINGHAMPTON, N.Y. 
13904, AC 607 723-3111 

Offices and Warehouse 10 Alice Street 
COMPUTER GRAOE 

ELECTROLYTIC SALE 

LARGE QUANTITIES AVAILABLE 

Minimum Order 10 pes. 
All Sizes— 5W ea. 






VANGAMO 



SPtACUE 



VALUE SI 

500 MFD 200 VDC 2 

1,250 MFD-180 VDC 2" 

1,500 MFD 100 VDC 2" 

3,500 rVIFO^ 55 VDC 2" 

3,500 MFD- 75 VDC 2" 

36 VDC 2" 

45 VDC 2" 

19 VDC 2" 

18 VDC 2" 

16 VDC 2" 

15 VDC 2" 

13 VDC 2" 

12 VDC 2" 

10 VDC 2" 

10 VDC 2" 

e vdc 2' 

10 VDC 3 




5,000 MFD 

5.500 MFD 

11,000 MFD 

11,500 MFD 

12,500 MFD 

10,000 MFD 

14,000 MFD 

15,000 MFD 

15,500 MFD 

15,000 MFD 

25,000 MFD 

30 000 MFD 

60,000 MFD 

20,000 MFD 

15,000 MFD 

35,000 MFD 

7,000 MFD 

3,000 MFD 

2,500 MFD 

3,750 MFD 






■ f 



* ■ 



5 VDC 3" 
15 VDC 2V*"*AVk" 

15 VDC 2V* t 'x4 % A" 



2" x 6" 
1avi'x4W 

1i/e'x4W 

2* x4H" 



12 VDC 

13 VDC 
25 VDC 
45 VDC 
75 VDC 

Np COD. Include necessary postage 

* JUST BOUGHT OUT ORIGINAL CASE FOR 
CB RADIO. Includes mtg bracket for mobile 
use & slide-in chassis. Holes p re-punched for 
power supply transistor & power cord, May be 
used for mobile power supplies, P. A. system or 
speaker box or many other uses. Size - 3M" H x 
7" W x 8%" D, Weight 3 lbs. Original cost 
$9.95. Our price ...... $1.95 

M1N ORDER $5.00 FOB Bingham ton 



Active Filter Features 
Low Power Consumption , 

A new hybrid active filter, the Model 
FS-60. requires only 0,3 mW of power at 
±2V, making it particularly suitable for use 
in battery-operated equipment. The unit 
sells for $10 in large quantities. Operating 
in the frequency range from dc to 10 kHz, 
the FS-60 features multiloop negative feed- 
back for high stability and a Q range from 




0,1 to 500. Other key specifications 
include a voltage gain adjustable to 40 dB 
and the ability to attain complex zeros 
anywhere in the S-plane. Bandpass, high- 
pass and lowpass outputs are available 
simultaneously. The filter employs encap- 
sulated hybrid circuit construction and is 
housed in a 14-pin dual in-line package 
measuring 0.804 x 0.336 x 0.474 in. 
Complete specifications and additional 
pricing data are available from Kinetic 
Technology, Inc., 3393 De La Cruz Boule- 
vard, Santa Clara, Calif. 9505 L 

Those DGP Maps 

The three-dimensional maps that DGP 
Company is distributing make the normal 
topographical maps look like junky gas 
station maps. These not only are a great 
help to anyone working on VHF, they are 
about the last word in a fancy wall map. 
Businesses are grabbing these up for 
decorating their walls, they are going up on 
hamshack walls, and they are being used as 
gifts for sportsmen. 

The detail on these maps is hard to 
believe. They get right down to even the 
little dirt roads! Each map covers an area 
about 100 miles by 70 miles and every 
mountain is clearly shown both with con- 



134 



73 MAGAZINE 





HIGH MFD CAPACITOR SPECIAL 

A2040Sangaimo or Pyramid 4Y+" x \¥a" 

4000 MFD 50V 50 . . ,5/2.00 

A2039 Pyramid 4!i" x 3" 6000 MFD 

75V . 75 . . .3/2.00 

A 2035 Mai lory 57=" x 3" 31,500 MFD 

25V ........ BRAND NEW 2,00, .3/6.00 






CAPACITORS 
Stock No. Mfd. Vdc. 



A2010 

A2011 

A2012 

A2013 

A2014 

A2015 

A2016 

A2017 

A 20 18 

A 2020 

A2021 

A2023 

A2025 

A2026 

A2027 

A 2028 

A2029 

A2030 

A2033 

A2034 

A2035 

A2036 



1000 

2000 

22 

45 

260 

500 

20 

1 

22 

.01 

.15 

.10 

.001 

.05 

100 (Pf) 

.0022 

47 

5 

,01 

.03 

31.500 

50 



50 

50 

6 

75 

75 

100 

350 

525 

50 

600 

50 

200 



Twist Lok 
Twist Lok 

601 D .75 
601 D 

Twist Lok 



P.C, mount 



50 
25 
100 
400 
25 
12 



Miniature 



P.C. mount 



.75 3/2.00 

1.00 

5/1.00 

3/2.00 

1,00 

1.00 

/1.00 

5/1.00 

10/1.00 

8/1,00 

10/1.00 

8/1.00 
20/1.00 
20/1.00 
20/1.00 
20/1.00 

8/1.00 
15/1.00 
20/1,00 
10/1.00 
2.00 
10/1.00 



A4016 FET Field Effect Transistor To-18 

25 Volt Source to 

Gate N Channel ,50 5/2,00 

A4017 Tunnel Diode Similar 

to IN 37 17 .50 5/2.00 



MISCELLANEOUS 
ITEMS 



A801O 

A9004 
A904G 
A9001 
A9003 
A9032 



INTEGRATED CIRCUITS 



Stk. No. 
A3000 
A3001 
A 3008 
A 3002 
A3003 



Typi 

907 

914 

914 

915 

923 



A3007 3M4-923 
A3005 1M4-925 
A 3004 926 
A3006 926 
(FP-Flat Pack) 



Case Function 

TO-5 Four input gate 

TO-5 Dual 2 input gate 

FP Dual 2 input gate 

TO-5 Dual 3 input gate 

TO-5 JK Flip Flop 

FP JK Flip Flop 

FP Dual 2 input gate 

TO-5 Buffered JK Flip Flop 

FP Buffered JK Flip Flop 



.75 
1.00 
1.00 
1.00 
1.00 
1.00 
1,00 
1,00 
1,00 



SILICON CONTROLLED R 



FIERSfSCR'S) 



A 4 200 
A4201 
A4202 
A4203 



50 Volts 
100 Volts 
200 Volts 
300 Volt v s 



1 Arnp TO-5 
1 Amp TO-5 
1 Amp TO-5 
1 Amp TO-5 



4/1.00 
2/1.00 
3/2.00 
4/3.00 



2000 Ohm Multi turn trimmer 
To-3 Power Transistor Sockets 
Fan Motor 110 AC 
Sun Sub-miniature slide switches 
Fuse Holders (Panel tvpe) 
Dialco 28 Volt pilot light bulb 

and assembly 
A9060 Mercury Wetted Relay Clare 

HGS 1059 

A9063 Nickel-Cadmium Batteries 1.25 

Volts, 4AH 
A2031 Miniature variable Capacitor 

3-75 uufd 
A9068 Printed circuit boards (no 

components 
A9069 Printed circuit boards with 

components 



.75 

8/1.00 

1.00 

3/1.00 

6/1.00 

3/1,00 

1.00 

1.25 
3/1.00 

8/1,00 
5/1.00 



A4019 
A4022 



A 4000 
A4001 

A 400 2 
A4003 



TRANSISTORS 

2N3904 Motorola 5/1.00 

MP1546 PNP Germanium 
Power transistor 
100W .75 3/2.00 

2N277 Motorola Power Transistor 

PNP Germanium 55 Watts .75 3/2,00 

2N1183B RCA Power Transistor 

PNP Germanium 7,5 Watts .7 5 3/2.00 

2N1204 Motorola 5/1.00 

2N231 PNP Germanium (RF) 5/1.00 



A4005 
A 4005 
A 400 7 

A4008 

A 4009 

A 4032 
A4050 



A 40 10 
A4011 
A4012 
A4013 
A4014 
A4015 
A4029 
A4040 



IN 629 
IN 1200 
1M2326 

1N3195 

IN 3255 
IN 3208 
1N2071 



1N75TA 
1N3039A 

1N3822 

1N3000B 

TN3048B 

M3.0 
1N429 
IN 3048 



!4 



Diodes 

Hughes PIV 1 75, 30 nrra ■ 
Svlvan^a PIV 100, 70 ma 
RCA Rectifier Piv 200, 

1 00 ma ■ - - 

RCA Rectifier PIV 600. 

5O0 ma ....»*.., 
RCA Rectifier PtV 600, 

-J \J U Ml a . i , » . ^ i . . a i ■ 

Motorola SH icon Roctifie 
50 Volt^, 15 Amps . . 

Sylvania Bullet Diode PIV 
600, 750 ma ....... . 

Zener Diodes 

5 1 Volts. 400 mw 

62 Volts. 1 Watt ...... 

36 Volts, 1 Watt 

62 Votts. 10 Watts .... 

150 Votes, 1 Watt 

3 Volts, v, watt 

5.6 Volts. 1 Watt 

150 Volts, 1,7 ma 
(Matched pair} ,►».♦, 



■ B/1.00 

. a/i„oo 

■ 5H.00 

10/1,00 
10/1.00 

, 3/V00 
. 8/1.00 



. .5/1.00 
. 3/1 00 

. . 5/ 1 OO 

.21 00 

. 3/1.00 

.4/1 00 

. .4/1 .00 



.75 



Spe 



rial w ' th every order of ten dollars or 
U,DI more, choose two more dollars F REE. 



Lots of other items — send for free flier: AU 
merchandise fully guaranteed. Please include post- 
age: excess will be refunded. 



A 



DELTA ELECTRONICS CO. 

BOX 1, LYNN , MASSACHUSETTS 01903 



tour curves as with the topographical maps, 
but also by being raised. The raising is 
exaggerated by a three-to-one factor to 
make the mountains really stand out. 
These are the most detailed maps ever 
produced and were done from actual 3D 
aerial surveys. 

Any time you find yourself stuck for a 
great gift for a friend (or yourself), one of 
these 3D maps will make a lasting impres- 
sion. DGP Company, Box 431, Jaffrey NH 
03452. 



GET MONEY 

Guaranteed top money for any p+ece of surplus 
equipment Payment in 24 hours. We also p4y Sfcip 
ping, insurance Call collect or send list for quic* 
quote. SPACE ELECTRONCS CORP. 1 1 Summit Ave 
East Peterson, New Jersey. (201) 791 "5050 



*TW0-WAY* 

COMMUNICATION CRYSTALS 

AMERICAN CRYSTAL CO. 

PO Box 2366 Kansas City. MO 64142 
(816 842 5571) 



MAY 1970 



135 






- 





>,:-., :,;■::::;;•:. -^i^;.; , 



NEW 




Patented Challenger Series Balun Fed 

lnverted*Vee®2KWP and 4KWP Antenna Kits 

Simple to set up. hhperformance antenna systems. 
Kits include — patented encapsulated broad-band ba- 
lun, 200 ft, antenna wire, insulators and complete in- 
structions Tor erecting as either Mono 40 or 30M 
Inverted-Vee or Fan-Dlpole 40/80 Meter Inverted-Vee. 

2KW Peak Model CIV2KWP $18,95 

4KW Peak Model CIV4KWP $25,95 

Prices postpaid continental U.S.A Add tax if appli- 
cable. At your dealer or order direct from Telrex for 
fast personal service. Send for tech. & price bk, PL 70 



~felrex 



ANTENNA LABS 

Asburv Park, N. J, 07712. 



NEW G&G CATALOG! 

MILITARY ELECTRONICS 



24 PAGES, crammed with Gov't Surplus Electronic 0«mr - the BLggtat 
BmrgaLn Buy ft In America I Ii will p*y you to SEND 25c for your copy - 
Refolded i* 1th your fir at order, 

UC-645 TRANSCfJVER i& tub**, 435 to 50G Me. 
Easily adapted for 2 way voice or code on Ham t 
Mobile, THevisJon Experimental, and ClUzena 
Bands, With tubes, lens power supply #« A AJE 

In factory carton. BftANDNEW ^10*7-1 

SPECIAL PACKAGE OFFER; BC-645 Transceiver, pynmmotor and ail 
accessories* including mount Log * UHF Antenna Assemblies, control box, 
complete set of connectors and pluj*, CO A ©C 

Brand New »•••••••••**•«•*** #iO#V3 




R4I COMMAND RECEIVER ARC 190-550 Ke, Commercial 
lAte modri. Excellent Condition »,*••»•■ 



«*t#***i« 



$12.95 



Cl*#:- 




•xd&ss^ 




■ ' 





R-4/AIR-2 RECEIVER 234-25a Mc. Tunable, complete with 11 tube* 

Excellent Used ,»,,,..,*,. ....*.*,,. ..«•». ..., $&.9S 

BRAND NEW, Including dynamolor ,.*.*.*,*.» ..»**■..,.., $9,95 

&C-659 FM TRANSMITTER/RECEIVER 
27 to 38.9 Mc. Xtai control on any two pre-selecteti 
channel « f 60 channels. Complete with U tubes 
speAker f meter, l9xl2ix€j'% #ma r#% 

^tn ll , >l>II , >II 4ti|||||t4iiitiiii ^^ ^fc ^» *^F ^^ 

VIBRATOR POWER SUPPLY for above, 6V, IJV or 
24V (specify when ordering)* Like Kew, ftl 16.95 

McELROY AUTOMATIC KEYER Suitable lor keying transmitter or far 
code practice* Has pliuto-eleclric cell and sensitive relay. CI O OK 
HP v 60 cycle AC. Complete with tube^ Excellent Used , . , .<^1 *iVJ 

— ' 

PE-219 BATTERY CHARGER Charge one or two 6V bfttlertea at 7 ampa. 
from 6, 12 of 24 volt source. Uses one plug-tr. vibrator. Complete with 
10* power cord. In metal case 11 x 10 x S|'' deep, £_ ^ - 

'A eight 40 lbs. Signal Corps equipment. NEW , t »,. ^*Y«tO 

TELEPHONE TYPE RELAY Made by J, H. Bunnell, has adjustable 
sensitivity. 150 ohm coll. Site 3| x 4 x f f p , Shpg wt 3 lbs, NEW $3.95 



6C405 INTERPHONE AMPLIFIER Easily converted to home 
Intercom system* Uses pall of 1619 tubes, delivering 10 watts 



power. Brand New. 



*.■>■>.».■ 



$2,35 Excellent Used. 



or oUlce 
of audio 



Range 

HEctivrm, 

I 90-3*0 KC. 
3-6 Mc, 

i""i v WC • - - 
* ■ 3 ■"■■3 R*C, ■ » ■ 
T»AN3MlTTERS 
4^3.3 D(,.^ . . 
3.1-7 Mc, 
T-3\i MC. 
*, 13 Mc 
3-4 MC, 



SCR-274-N, ARC 5 COMMAND SET HQ! 

Eic Line 



116.91 

J 16 30 
14 93 



Typ* Urrd 

Cflmoitte with Tubes 

Bt-«S3 
BC-4 54 
BC-433 

Bt-23 

eofnniet* with 

•C-457 

•C-431 

T-ll 

. T-19 



New 

113. 

413 
117 
119. 



SAAND 



TutHPt 

i 6. S3 
33 
91 



117. 



lit 
3 9 
112 



50 
30 
91 
30 

91 

99 

30 

,93 

90 



917. 

122 30 
1*1 50 

121 SO 

fti.fi 

312. •» 

121 30 
11 1 93 
lit, 91 



TERMS; 25% Deposit with order, balance CO. D. -or* Remittance In full. 
Minimum order $5,00 F t O. B. NYC. Subject to prior sale and pric change 

GIG RADIO ELECTRONICS COMPANY 

47 Yiarrmn St. i2nd Fl New York, NT. 10007 Ph. 212-267-4605 



- 






FROM 
TELREX 



advised by my Lawyers th r 
i ns loriM ver 

mis 
bi 




r insist thet you print 
3h Id be boiled in oil 



n 
ov 



Army Manual 

The "Tech Manual" format for March is the 

best yel! Kudos to whoever thought that one up! 

Fritz WB4MSJ 

There were many comments from our ham- 
type technicians regarding your March issue on 
the front cover. All in all, they thought was a 
darn clever idea and they also made many nice 

comments regarding the quantity and quality of 

technical articles. I thought the amateur radio 

news page in the March issue was most interesting 

and 1 have removed these two pages and put 

them on the company bulletin board* 

R.A. Kobold 

Manager, Cust- Svc. 

Galaxy Electronics 



Cover Award 




March 1970 




Originality 


10 


Color 


10 


Copy 


10 


Type 


10 


Layout 


111 


1 'esign 


10 


Content 


10 


Technical 


10 


Paper Stock 


10 


Appearance 


10 


Total 


100 



Congratulations 
de WA4NED 

Re - the March issue - clever cover. The 
w NOT-TOQ-TECHNICAL MANUAL" bit is 
especially right Did you check pages 62 through 
67? The guy (Bob Manning K1YSD) must be 

sick, 

Everett G, Taylor W6DOR 

4100 Worthington Dr, 

North Highlands CA 



as a professional 
am enjoying those 



Y? 

A couple of things, 
communication engineer, I 
Extra Class articles. But tell me, what little 
gremlin, or type lice, made off with the letter Y 
ii) Table 1 on page 101 of the February issue???? 
I specialty since RY is one of the favorite test 
letters on the circuits, along with the quick, 
brown fox. 

Next the February issue was delivered here in 
San Diego on 20 February, so those announce- 
ments of events happening before then were of 
only historical interest ( whatever that may be). 
Looks like you should insist on a longer lead-time 
if the item is to be of value. 

Les Harlow WB6ZNW 

5015 Cape May Ave. 

San Diego, California 



136 



73 MAGAZINE 












\1\ question is: V? 

You left it out of the RTTY list on page 10 1 
of the February 1970, 73 Magazine. 

And 'V is so important it's the other hall" 
of *R Y 1 one of the most familiar terms in RTTY, 

C.L. "Bob" Engelbreeht VOIBL 

31 Cowan Avenue 
St. John's* Newfoundland 

Yoiksf Y is coded 1-3-5 and it most assuredly is 
one of the important letters for TT'ers. 

. . . Wayne 

League Representation 

As :i relative newcomer to amateur radio ami 
a subscriber to your magazine I am only disap- 
pointed in one thing, that your maga/ine doesn't 
come more often. I feel as I'm sure most of your 
subscribers do. that you are the only ham 
anigazine which truly represents the amateur. 

By ail means amateur radio should have a 
lobby in Washington, if the ARRL doesn't push 
for a lobby we should ask who are they repre- 
senting, amateur radio or their own little station 
in Conn. If the ARRL doesn't react on this it's 
time everyone reacted on them. I myself am not 
a member of the ARRL and do not intend to be 
until I feel they would be representing me and 
not their own interests. 

As 1 have mentioned previously I am truly in 
love with your magazine. There has not been one 
article which I have left unread and undigested. 
It's truly worth every cent of it's price, even if 
you have raised the price. Now I'd like you to 
listen to one of my gripes. Even though I am a 
Novice I do spend most of my time scanning 
across the phone bands. And I must say Vm very 
disappointed with the general conversations. Now 
don't get me wrong - listening to a ham tell 
another how he gets such great modulation 
excites me just as must as the latest hit record, 
and Til have some fish stories to tell too when I 
get my General, but is this all hams have to talk 
about? When is the last time you heard an on the 
air debate about the latest I CC proposal or some 
discussion over an amateur lobbs : What I pro- 
pose is this, a net be established to talk over these 
things, a place where some meaningful discussion 
might take place. 73 and other magazines might 
keep the net informed of latest developments and 
an FCC-net hotline might be established. Wayne 
and other writers might have some otvthe-air 
editorials to promote discussion. Other subjects 
might be discussed which generally bring to harsh 
a reaction from the general ham population, such 
topics might include, SIX. RFL1GIGN. and 
POLITIC S Anyone could therefore tune in on 
the net and find out what's happening on the 
amateur scene today. Some amateurs who don't 
subscribe to 73 aren't even in the right decade, I 
think that the net would be especially inspiring 
to SWLs contemplating becoming hams and 
Novices interested in becoming Generals. 

Tim Rulon WN2KQD 

12 Morahopa Rd. 

Centerport NY 

Urgently request your leadership in pro- 
motion of f \1 Unuout amateur world. In my 
humble opinion I M has the potential to nullify 
CB. restoring Amateur Radio to its rightful place 
in public service. The excellence of I M as a 
communications mode for civil defense, etc. will 
bring about a revision of trends and policies. 



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swinging public service back from CB to ham 
radio. Only hope the League isn't too blind to see 
this obvious fact nor too set in their ways to 
realize FNTs potential to rescue amateur radio. 1 
am confident in you and your staff to provide 
interim leadership and technical information 
until Newington's Ponderous Pachyderm starts to 
move. Can anything kill their apathy? 

M.N, DeBlasio WA2HCD 

We agree that FM has the potential to nullify the 
inroads made on public service by CB — which 
could prove highly beneficial to amateur radio. 

. . . Ken 

Big Brother 

1 wrote a letter to the League suggesting that 
instead of taking frequencies away from us, they 
should request the FCC to open new frequencies 
to us as an incentive. My reply from headquarters 
stated, in essence, that we should trust in the 
judgement of big brother in that they know what 
is best for us. Builv for them. 

EarlWAlKYW 

7 Randolph St. 

Arlington MA 

Killing the Big Thump 

For better than two years now I have been 
fooling with an 813 GG linear (two in parallel). It 
is built entirely of surplus junk ( and I mean that 
in the strictest sense of the word!). 

One of the biggest problems was the power 
supply which is made up of a 2500—0-2500 
power transformer, 866 filament transformer, 
1616 rectifiers (I used to have 866 A's. . .they are 
directly interchangeable), and two gigantic oil- 
filled filter capacitors. With power supply turn-on 
Pd get the "big thump" and the most beautiful 
flash in the 1616s! It would then proceed to 
blow the 10A slo-blow*s in the line plug plus the 
20 amp circuit breaker in the shack! 

150 W 
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I went through 6-866 A's, and 4-16 16*s and 
kept thinking it was scrounging soft or, bad 
rectifiers. The fact is, they couldn't handle the 
terrific surges!. I became aware of this fact after 
reading an article by R.T. Brackman and M. 
Weinschenker (73, Page 77, Jan, 4 70) on silicon 
rectifier diodes. I never realized there could be 
that much surge. In the Jan. 4 69 issue of 73 Mag, 
on page 22, W9VEY offered a solution. I didn't 
like this simply because I did't have a spare relay 
and the 20W, 5 kO resistor. 

So. . .in my power supply I wired in perma- 
nently a 150W light bulb in series with one of the 
primaries. This is turned on first and then after a 
few seconds is shorted out to let the full 2500V 
in. This serves two purposes. . .one-it got rid of 
the "big thump" and the ensuing "big blow" by 
fuses, and two-I now have a 800V low voltage 
supply built in! 

The light bulb is mounted in a plplug-in type 
light bulb socket so that if I have to change 



138 



73 MAGAZINE 




bulbs, li J I I liyve to do is unscrew the old one and 
screw in the new one. It is mounted on a rotary 

switch* 

Wayne Jinske WA9SSH 

Custer WI 

I wonder if it is not possible that Wayne's 

editorial stand concerning the League is not 
having some indesireable side effects. 

Have you listened to W1AW code practice 
lately? Could it be that some of those who like to 
tune up on top of the code rcssion or come 
slipping in from the Northeast over it might feel 
they are in their own way supporting Wayne in 
his battle with the league? 1 do not think 73 
wants that sort of support. Perhaps these indi- 
viduals do not listen to anyone or any publica- 
tion. In any ease I, in behalf of others who use 
the code practice service, would appreciate your 
help. 

Bob Cutler WN^YED 
Glenwood Springs CO 



The FM Route 

My wife and I just got back from a vacation 
trip of 2 weeks on the newest of highways: the 
new 146.34-146,94 open repeater FM highway. 

I have been an amateur for many years, but 

never enjoyed anything as much as this trip on 

the highway open to the amateur today. As soon 

as we got 50 miles from Bloomineton, ML, I took 

the mike and said. This is W9JFP/9 mobile/ 

From there on, I had company all the way to 

California and back with the open repeaters on 

.34-. 94 FM. Made hundreds of contacts — all so 

friendly I couldn't believe this was amateur radio. 

I was 60 miles from Tulsa and listening on .94 

and a very pleasant voice broke squelch with: 

"This is WA5LVT, Tulsa Repeater; the time is 

6:00 u-m/' This was heard every ten minutes for 

the time I was in range, which was about 60 miles 

either side. Near San Diego I called but heard 

only a few stations and no responses, because this 

was an exclusive tone operated closed group; 

same story in Los Angeles, but on the way home, 

when we were 60 miles from Las Vegas. I got a 

reply from the open repenter in Las Vegas; and 

all the way back to Milwaukee, for 2200 miles of 

driving, I had company almost continuously 

thanks to my trusty 4Iv (which is old enough to 

retire) and the open repeaters on 146.34/146.94 

FM. When we got within range of Chicago again 

in the exclusive area, couldn't make a contact 

because the repeaters were not open. All I can 

say is thanks to you and the 2 meter FM open 

repea ters. 

Vic Weissbrodt W9JFP 



The Chicago repeaters are open to transients, Vic. 
But the output there is 146,75 MHz because .94 
is too active on a simplex basis. The stations you 
heard in San Diego were undoubtedly the same 
ones you heard in Los Angeles — Remotes Oper- 
ated By Insociable Nets (or "Robin/' as it's 
called in California. ) 

. , . Ken 

FM Fringe Area 

I have enjoyed your magazine ever since I 
started mooching off a local fellow ham. We have 
decided that I need my own subscription, 
especially since I tend to retain the FM articles, 
which I find excellent. 




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Mid-Missouri is a fringe area of VHI , but it's 
coming along, especially on I M i 146.94). Keep 
those Vlll articles coming and Congrats on a fine 
magazine; the March issue was beautiful! 

Jos. McGrevv III WA0Z1K 

Eldon MO 

On Spectrum Utilization 

I have just recently returned u> stateside 40 
meter operation and found the QRM level near 
that experienced overseas, Sol would like to pass 
on to you my thoughts on the usage of amateur 
frequencies by broadcast stations. Here are l\u> 
possible avenues of attack to remove some of the 
congestion from the air. 

First and probably the most likely to show 
results in cost versus listener audience, I should 
think that the SWBC cost of transmission far 
exceeds the justification number of listeners. 

With the present budget cuts, the time seems 
right for amateurs to point out the cost of 
broadcast compared to that of amateur radio. On 
the transmitting end. broadcast is expensive and 
amateur radio costs practically nothing - and on 
the receiving end, SWLs pay nothing, while 
amateurs pay to be licensed. 

Now the second course, by the very presence 
of broadcast stations in our bands, it would seem 
that they are not concerned by the interference 
we cause. When you consider the difference in 
power levels between amateur and government 
transmitters we can do them little harm; there- 
fore, I suggest some joint frequency usage. In the 
21 MHz band (above 21.450) harm could easily 
squeeze in contacts if cost reductions took some 
transmitters off the air and hams were allowed to 
llll in the gaps. I admit we would be competing 
with those who "come up on any clear freq" but 
we live with them now. 

Stephen Miller WB6TVT (KA2SM) 

San Diego CA 

Dockets 

The FCC has recently issued a notice of 
proposed rulemaking concerning, among other 
things. (1), Amateur radio license fees, and (2 
Mil repeaters. I have the following objections: 

(1) The increase in license fees would be in 
direct opposition to the federal Government's 
anti-inflationary policy. An increase in fees to the 
suggested level would make the cost of u license 
prohibitive for many amateurs, and when the lees 
are further increased in the future, as would 
inevitably be the case, amateur radio might 
possibly become a thing of the past owing its 
demise to being ''licensed right out of existence/* 

(2) Regarding the propositions to (a) elimi- 
nate crossband links on VHF repeaters, (b) 
confine the repeaters to specific segments of the 
6 and 2 meter bands, and (c) limit the power 
output to 250 watts, I am in direct opposition In 
all three proposals. Since VHF repeaters arc 
amateur stations licensed to amateur's as remote 
control transmitter locations, the proposals 
named above, (a), (hh and (c) arc all in direct 
conflict with amateur licensing rules and operator 
privileges as stated in the FCC rules and regula- 
tions. Amateur operation is permitted on the 
bands according to the class of license held In 
the operator and method of modulation 
employed. NOT according to type of operation. 
This cannot be regulated in the proposed way 






140 



73 MAGAZINE 



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unless the current rules and regulations concern- 
ing operator licensing and privileges are greatly 
altered. Hence, the proposals to confine VHF 
repeater operation to certain segments of the 
authorized bands and limit their power output is 
in direct violation of the current rules and 
regulations. 

The proposal to eliminate crossband links on 
repeaters would greatly inhibit repeater activity 
and growth, and would make it impossible for 
many repeaters now present to continue oper- 
ation. This provision also violates all previous 
I CC policy because crossband operation (A0) is 
presently acceptable on all bands above 51 Mil/ 
according to the current rules and regulations. 

The inhibiting of VHF repeater activity and 

future growth would present a great setback to 

emergency communication networks, and thus 

the FCC. by adopting these proposals, would be 

greatly reducing the ability of amateur radio to 

serve the public interests, which is also in obvious 

conflict with present FCC policy, 

Thomas McLaughlin WB4NEX/9 

N. Manchester IN 

Open Letter to Hams Everywhere 

Dockets 18802 and 18803 endanger the 
existance of amateur radio as we know it toda\ 
Individual and group action on these dockets can 
help, provided that both individuals and clubs 
respond in the form of comments to the ICC and 
cards and letters to congressmen and the White 
House. 

Note that the ARRL has not been a party to 
Docket 18803 other than to verbally support the 
Buffalo petition. *L ! nfortunately. the only part of 
the Buffalo petition that filtered into Docket 



18803 has to do with logging and tone access. 
ARRL is opposed to \HH02 on grounds that the 
amateurs do most of the work in licensing and 
policing the bands themselves. 

Three steps should be taken immediately, , . 

1. Request an additional 30-60 days for 
reply comments on Docket 18803. The 
mechanics of obtaining comments filed - 
in order to file reply comments - requires 
more time for reply comment filing. 

2. File individual and group comments on 
Docket 18802 as soon as possible. 

3. Write to your Senator, Representative, and 
the President expressing your feelings on 
these dockets. (This pressure will also be 
felt back at FCC J 

Copies of comments should be retained for 
future use - it will do no harm to send a copy to 
ARRL also. In this way you let them know your 
stand. 

Need a Xerox? FCC needs the original plus 14 
copies of every thing you send them. The New 
fngland I M Repeater Assn. will make copies of 
comments from individuals only if the original 
is sent to us 

Gordon Pugh W1JTB 

Two -Party System? 

With advent of incentive licensing. I sort of 
lost interest in ham radio and lei my subscrip- 
tions to the four mags lapse. Recently. I came 
across vour Dec. '69 issue and after having read 
your remarks on the ARRL and reviewed the 
other material in it, my interest was stimulated to 
the extent that I am herewith renewing my 
subscription for three years- 1 would like to see 








MAY 1970 



T41 






■ 



TRANSISTOR AUTO RADIOS 



Brand new factory packed automobile radios, vintage around 
196 1 12 woH n*fl, ground, No choice of models. The 
exceptional sen&itrvity of an auto radio makes it superior for 
use in car. boat, truck, camper, etc., where you are quite a 
distance from xmtr location. This is also the best bind of 
radio to use with short wave conveners. Each with targe 
original equipment hi-fi speaker. Some with noise suppressor 
kit. High quality, most made to sell in the S100 range A real 
"f.nd." $1500 





2 METER ARC-3 



Just uncovered a batch of the famous ARC*3 
rcvrs & xmtrs with all tubes. Range 100-156 
mc, 8 xtl channels. Cheap way to get on 2 
meters, CO nets, JvlARS nets, etc. With con- 
version details, Rcvr $15, Xmtr $15: 



RF FERRITE CORE CHOKE 



Hi-permeability, ultra midget style, 
coated for moisture resistance, color 
coded* Used in *mtrs, receivers, con- 
verters, TV-peaking, Brand new, 
worth 40c each. Assortment of L8* 
27.0, 330 uh. Pack of 30, $12.00 value. 

#A-71 30/$1.00 180/$5.00 



TRANSISTOR MOUNTING PADS 



Round fibre glass insulating pads, used under 
3 legged TO-5, TO- 18, etc. Raises and in* 
striates transistors from PC board. Permits 
longer leads to be used with less danger of 
heat destruction. Adds professional touch to 
finished circuits. Bag of 50 pre-drilled pads. 

#A-3 50/11.00 300/$5,00 



PHOTOFLASH TRIGGER XMFR 



Thordarson #22R44 brand new, produces 15KV 
pulse. With spec, sheets, 

#22R44 $1,75 each 10/$ 15.00 



TRANSISTOR SOCKETS 



■ •%»■ 




Universal socket for 3 pin Transistors, 
Bag of one dozen $1.00 Stock #S-1 

Texas Inst. 10 or 14 lead flat pack 
socket for test or prototype work. 
Lists for S3. 70 - Our price only 
$1 + 00 brand new. 

TO-3 socket for power transistors 
made by AUGET. 6 for $1.00 



BLEEDER RESISTOR 




Above equipment on hand, ready to ship. Terms 
net cash, f.o.b. Lynn, Mass. Many other unusual 
pieces of military surplus electronic equipment 
are described in our catalog. 

Send 25c 1 for catalog #70 



JOHN MESHNA JR. 

19 ALLERTON ST., LYNN, MASS. 01904 
P. O. BOX 62, E. LYNN, MASS. 01904 



another group form similar to the ARRL, but 
with more progressive ideas and better represen- 
tation of the amateur body. Certainly others in 
hanidom must entertain this idea. You have the 
vehicle in 73 to bring them together - why not 
do something in a positive direction about it 7 We 
have a two-party system in government - why 
not the same in ham radio? 

Dick Dunn W1BPM 

Wayne - In your article "ITU Conference: 
Who lobbies for Ham Radio?" 1 think you have 
made a statement that is in error. If I interpret it 
correctly, you say ARRL is a "tax -free' 1 organiza- 
tion because it is a "non-profit" organization and 
you state that they cannot legally register a 
lobbyist to represent them with congress. 

I base my reasoning that you are mistaken in 
this matter on the fact that the March 1970 issue 
of the American Rifleman, the Official Journal of 
the National Rifle Association of America, states 
that it "is an independent nonprofit organization 
supported by membership fees" and, in an article 
titled "A Statement 1 ' by the president of the 
National Rifle Association, it is stated that "We 
do have a representative registered under the 
Federal Lobbying Act for the purpose of neces- 
sary contacts on national legislation affecting the 
rights of gun owners." 

Hence, Wayne, if it is legal for the NRA to 
have a lobbyist would it not also follow that it 
would be legal for ARRL to do likewise, if it 
wished to * 

Clayton C. Gordon W1HRC 

P.O. Box 85-West Main St, 

West Millbury MA 

Nonprofit does not mean tax-free. You will find 
that the NRA is not tax-free, that they are paying 
their way like any other business even though 
they are nonprofit. The ARRL saves thousands of 

dollars a year by being tax-free and this means 
that they cannot by law register as a lobbyist in 
Washington for amateur radio, 

. . . Wayne 
Democratic? 

Would you perhaps like to mention in a 

future column that while ALL licensed amateurs 

are eligible for "FULL 1 * membership in the 

ARRL. only those holding a general or higher 

class license are eligible to hold office. A quick 

look at the breakdown of licensees in the 

callbook will convince you that the ARRL is not 

by any meaning of the word a democratic 

organization. As a number two punch you might 

look into the awarding of the QSL bureau. I 

understand that this situation stinks to high 

heaven too. 

Col, D, Lester W1AER 

The League system of government is comforting 
to those in charge and a frustration to any 
members who are concerned over League HQ 
actions. The March 1970 QST editorial tells 
members not to write to HQ, just to their 
directors, if they have a complaint. The feeling, 
right or wrong, is that writing to the director is 
futile since this "representative" appears at HQ 
but one or two days a year of highly structured 
routine meeting work. This means that the 
possibility of any individual being represented is 
virtually nil. The boss that comes to work one or 
two days a year has no real idea of how the 
business is really going , no idea of the com- 
petence of the employees, and no opportunity 



142 



73 MAGAZINE 



SALE ONFAIRCHILD'ICs" 



•Brand Newf 'Lowest Prlcti 



400 



mc 



RTL-908 
RTL-909 
RTL-912 
RTL-913 
RfTL-914 
RTL-915 
RTL-923 
RTL-96G 



■ lliiiltMII«M*»< 



>l«»tt> 1 ■, 



Full Adder 
Buffer 

HaJf Adder 

Shift Register 

Dual 2 Input Gate 
Dual a Input Gate 
JK Flip FJop 

Dual Buffer 



m 4 44 * + m 



4 + 4-44 + * + ■■■■*»" 



GIANT 
tPOX* 



SALE 



ON 



GLASS 



AMP* 



to 2 *rnpi 



Micro 
Up 

PlV 



EACH 3 for 



100 
200 

400 

too 

800 
1000 



.04 
.07 
.08 
.11 

.16 
At 



15 

.11 

.21 

.29 
.42 
At 
.« 



How'* "MEMORIES" fpr 1970? 

D FaircMId 1 128 8 bit J2.49 

!_, Fairchild 9033 l& bit $3 98 

Q Philco PLSRI00 Dual 50 bit $12 50 
□ 4000 Bit Cor« Pianu $8.50 



Each 
3 for $2.75 



NFN HIGH POWII 
UHF TRANSISTORS 

□ 2N3632 ?3w 3a 

D Shocklay Diodai. 4 layars 3 for $1.19 

D Nton I Nixia Orivar 2N44I0 4 for $1.00 

D SCR/Triac TrJggar Diodai 4 for $1.19 



TEXAS! NATIONAL! 
FAIRCHILD 
COUNTING "ICV 

Guarantfdl W/Spt SAaafi Any 3 — 

10% Discount! 



HIGH VOLTAGE 

1 AMP erf* 1 



?5B Dtcadt Counter $4,95 

f5? Quad Latch . .„.„. 3.95 

SN7493.4 Bit Counter,. 4.95 

SN7490 Decade Counter 
5N747S Quad Latch 
SN744J BCD Decoder 
9301 I -to- 10 Decoder 
930* BCD Up/Down _ 
Counter (24-Pin DIP) 

9300 4 Bit Unk. Shift Register 2.49 
9304 Dual Full Adder 495 



PlV 

g 2oqo* 
D zooo 

4000 

5000 
6000 
6000 

n 10000 



SALE 

1.00 

135 

1.65 
2.25 
2*96 
3.50 
3.95 



SILICON 

RECTIFIERS] 



¥ I a *■■ iflll«l 



**»l" U4*ifllMtM I ■ * 



fHPI4HII**ilnaai 



LINEAR AMPLIFIERS 

9tM eecA, 3 for $4J$ 

H tTIS OP«««on*l Amp 
U 71 IC Samt Amplifier 



Fairchifd 741 OP, Amplifier* 

'frequency compe^sofad 709 $2.9fl 



POLY PAKS 



P.O. BOX 942 A. 
lynnfieid, Man, 

01940 



Term*: add postage. Rated: nel 30, cod's 25% 
Phon* Orders: Wakefield, Mass. (617) 245-382Q, 
Rata i I: 211 Albion, St., Wakefield, Mass. 



D 



sriM* 






whatever to hire and fire employees, no matter 

how bad things may get. The employees are the 

ones running the company in this situation, not 

the bosses (directors). 

. . . Wayne 

Printed Circuits 

I have just finished reading with some interest 
the PCB article by Ken Sessions, and would like 
to pass along a few additional hints for the 
benefit of those readers who are not familiar with 
circuit board fabrication. I have used these 
methods both for ''homebrew-* projects and also 
for the building of several items which have 
flown in NASA sounding rockets and other 
space-qualified hardware, they have worked out 
quite successfully with high resolution boards. 
We have achieved, at best, conductor widths of 
-02*' and spacings of .05*' under conditions which 
most amateurs can duplicate using conventional 
photo methods, However, back to the hints for 
use with the Bishop system. 

A "bug light" of 60 to 100 watts is quite 
satisfactory for a safe working light while work- 
ing with sensitized boards, and gives quite 
adequate light levels. 

A low-cost UV exposure light can be made 
from a desk-type fluorescent lamp by replacing 
the normal bulb with a "blacklight" lamp that 
emits light primarily in the violet and near-UV. 
Hope these additions to the info already given 
will be of use to someone wanting to turn out 
some home built gear. There are too few builders 
left on the ham bands. 

Jack Dugan W2IAX/2 

209 Catherine St. 

Scotia NY 



JEFF-TRONICS 



$375,00 



45.00 

5000 

250.00 

125,00 

.50,00 
.50.00 



Tektronix 532 scope with H plug in, 

Evr 
^* »■ ■<■■»*.*■■■",**.. ....... i 

PLUG-INS FOR TEKTRONIX: 

CA Dual-trace 75. 00 

E High-gain AC 45.00 

D High gain DC differential {made by 

La vote) . . . , . , , , • • * , 

Type 80 plug-in with P-80 probe & 

attenuators, unused. 

Genera* Radio 805-C Standard Gen, 

16 Kc-50 Mc 

G-r 650 A Impedance Bridge with copy 

of 650 PI Osc-Amp 

Brush RD 5616-1 1 Servo Analyzer. Inc. 

pen-drive amp. 50 mv, per line sensi- 
tivity. Brand new ..,,,... 

Gertsch PT-5R Ratio Tran. AC voltage 

divider ..... 

HP 350A Audio Attenuator Set. 

500 Ohms 20.00 

Beckman 1453 printer, . , . . , , . 150.00 

MB Electronics N662 Dynamic Range 

Expander , _ , .25.00 

Sanborn "Twin-Vise" 2 channel recorder, 

heat writing, with 2 DC amps fir preamp. 

For rack mount ......... • •'•.'•« 75.00 

Kay-Lab (Krrt'telr 50B25 Absolute DC 

voltage supply . , , . 100,00 

BC-221-N frequency meter 60,00 

TS-147B/UP X-band test set , . . 75.00 

TS-148A/UP X-band Spectrum Analyzer. 

New $100.00 Used . . . 75.00 

Facsimile Transceiver unit TT-66A/TXC 

(transmitting light source missing.) .... 35.00 
Elmec Af -67 xmtr, with M-1070 pwr. 

supply , 6000 

E Imac PMR-6A revr. & 12 v. pwr. sply. . . 42.50 
SBE S82-LA Linear Amplifier 150.00 

SPECIAL. CLEARANCE OF DISPLAY 
MODELS, NEVER USED. No trades. 
Drake TC 2, $250.00; TC-6. $200.00, T 4XB, 
8415.00, 2 C, $215 00; DC-3, $75,00. 

AH prices FOB Cleveland, Ohio. Catalog listing 
surplus electronics, new and used ham gear, 104 

JEFF-TRONICS 

4252 Pearl Rd. Cleveland, Ohio 44109 

749-4237 







MAY 1970 



143 






r. 



73 Readers' DOUBLE BONUS 



1 



Want info quick? Just check the box next to 
the name of the advertiser of your choice in the 
index below. We'll rush your name to the ffrm 
so you can get all the dope direct from the 
source. (Don't forget to include your name and 
address at the bottom.) 

ADVERTISER INDEX 



u Adirondack 86 


□ Martin Co. 123 


D Amateur Elect. Supply 35,121 


G Meshna 142 


□ Am&co 12 


□ Military 135 


O American Crystal 135 


tt Mosley IV 


n Antennas, inc. 77 


O National Radio III 


□ ArcoMfg. 133 


DOrd 77 


□ ATV 121 


D Pantronics 121 


D Bngor 134 


DPark 138 


d Callback 86,99 


□ Phase Corp. 95 


□ Camp Albert Butler 68 


□ Poly P B ks 143 


n Columbia 133 


D Quement 47 


u CB Radio 99 


Radiation Devices 133 


Dahl 97 


E Rohn 101 


a T; Dames 124 


RP Efectronics 99 


a Delta 135 


□ Sams 19 


□ Denson 82 


D Sentry 43 


E Dow Trading 123 


a Signal One 39 


D Epsilon 97 


D Spectronics 53 


i"-i Estes 63 


D Stuhlman Eng. 13 


n Evans Radto 82 


c Swan 56,5? 


a Fair 139 


c Swan Antenna 61 


D Freck 91 


DTelrex 136 


d Galaxy II 


Q Tower 140 


n Gateway 140 


OTri Rio 139 


n Good heart 137 


D Tristeo 121 


d Gordon, H. 65 


□ Vanguard 45, 72. 123 


G&G 136 


n Varitronics 33 


n Haf strom 61 


Q Vibroplex 97 


D Harrison 72 


a Western 134 


Q Heath 23 


D Woodside Research 59 


D Henry 17 


D WRL II 


□ H&L 137 


D World QSL 99 


a International Crystal 15 




n James Research 138,139 




Q Jan Crystal 97 


73 Magazine 


Janel 134 


P Handbook 76 


□ Jetf Ironies 143 


O Gunsmoke 124 


□ Johnson, Stan 121 


O Maps 116 P 117 


n Lewispaui 138 


Q Subscriptions t04, 105, 11t 


□ Libert y 141 


D Books 71 



Haven't got time to browse through the ads? 
Just put an X by the subject that makes you flip. 



D Antennas 

n Coaxial Relays 

□ Code Practice 
D Components 
D Converters 

a Crystals 
D Equipment Dist. 
D Integrated circuits 
n Keys, Keyers 

□ Linears 

n Oscillators (code) 

□ Oscillators (rf) 



□ PC supplies 

□ Preamps 

□ Receivers 

c Receivers (FM) 
n Surplus Elec, 

□ Towers 

□ Transceivers (FM) 
n Transceivers (VHF) 

□ Transceivers (SSB) 

□ TV/Fax 

□ Video Tape Recorders 



MAIL TO 73 Inc., Peterborough NH 03458 



Name _ 



_Call 



Address 



L 



Zip 



d 



PROPAGATION CHART 

J. hL Nelson 
Good O Fair (open) Poor Q 



May 1970 



SUN MON TUES WED THU* 



FU 



iAT 



3 




®(jj) @ 13 



24 25 26 



f 






EASTERN UNITED STATES TO; 







GMT: 


00 


02 


(H 


06 


Oti 


10 


12 


14 


16 


16 


20 


23 






ALASKA 


it 


M 


LI 


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7 


i 


74 


It 


14 


14 


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AUCiEKTlNA 


21 


21 


|4 


14 


~v 


74 


1JI 


21 


21 A 


21 


11 


ii 






AUSTRALIA 


21 


21 


14 


14 


711 


fl) 


14 


\i 


U 


14 


21 


2{ 






CANAL I U £ 


1 
31 


14 


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ENGLAND 


M 


7 


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14 


14 


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14 A 


1*4 


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HAWAII 


21 


21 


14 


7A 


7 


7 


^ 


14 


1 IV 


21 


21 


21 






INDIA 


14 


7A 


7K 


70 


711 


7H 


14 


14 


it 


Ll 


14 


11 






JAPAN 


n 


11 


14 


Tit 


711 


7H 


- 
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14 


14 


II 


1* 


14 






MEXICO 


21 


14 


14 


1 


td 


■ 


Li 


I4A 


21 


21 


31 


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14 






7b 


711 


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1411 


t4 


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14 


14 






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PUERTO HI CO 


14 


14 


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23 


21 


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11 


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21 


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CENTH 


AL UNITED STATES TO: 





ALASKA 


14 


14 


14 


7A 


i 






7A 


14 


ll 


14 


14 


ARGENTINA 


21 


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14 


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14 


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M 


14 


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14 


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21V 


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21 


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14 


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214 


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711 


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713 


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21 


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A = Next higher frequency may be useful also, 
B = Difficult circuit this period. 



144 



73 MAGAZINE 




Here's a transceiver designed for the amateur 
who would rather spend his hard-earned radio 
dollar on performance than frills. The 
NCX 1000 is built to meet the demands of the 
operator who needs and desires a high perfor- 
mance SSB-AM-CW-FSK rig with solid-state 
dependability and plenty of power. Add to this 
the convenience of having your transmitter 
(including linear amplifier) , receiver, power 
supply, and monitor speaker in a single, com 
pact, smartly styled 59 pound package. 

So let's look at the NCX-1000, starting with 
the double-conversion, solid state receiver. 
After the received signal is processed by a 
double-tuned preselector, a stage of RF amplifi- 
cation, and another preselector, it is applied to 
the first mixer for conversion to the first IF 
frequency. The first IF contains passband filters 
and a stage of amplification. A second mixer 
then converts the signal to the second IF 
frequency for additional processing by a 6-pole 
crystal-lattice filter and four IF stages. Finally, 
the signal is detected and amplified by four 
audio stages. The unparalleled high dynamic 
range lets you tune in weak stations surrounded 



by strong interfering signals. The result? High 
performance for SSB, AM, CW, and FSK. 
Sensitivity of 0.5 EMF microvolt (for a 1Q db 
S-N/N ratioh 

In the transmitter you'll find three stages of 
speech amplification followed by a balanced 
modulator, a crystal-lattice filter, a filter ampli 
fier, and an IF speech processor (clipper), A 
mixer converts the signal to a first IF frequency 
for processing by two crystal passband filters, 
and two IF amplifiers. A second mixer converts 
the signal to the transmitting frequency where 
it is amplified in five RF stages before it gets to 
the grid of the 6BM6 driver. Final power 
amplification takes place in a forced-air-cooled 
8122 ceramic tetrode which feeds the antenna 
through a pi network. Other features? You bet! 
Grid block keying for CW, Complete metering. 
Amplified automatic level control (AALCL 

So here's a package that can give you 1000 
watts PEP input on 80 through 10 meters, 1000 
watts on CW, and 500 watts for AM and FSK. 
The speech processor lets you double your SSB 
average power output with minimum distor* 
tion. No frills with the NCX-1000. Just top 




performance. 

For complete (and impressive) specifications and details, write: 

NATION AL RADIO COMPANY, INC. 

fV/rCf 37 Washington St.. Melrose. Mass. 02176 



NEW SINGLE-BAND BEAM 
FROM MOSLEY 



The Classic 20 

WITH 

EXPANDED 

CAPABILITIES 

ON 20 METERS 







Model CL-20 



DON'T LIMIT YOURSELF! 

When you install a 20 meter beam, there is only one 
antenna investment you can afford . . . The NEW CLASSIC 20 
with expanded DX capabilities, thanks to the new 
Classic Feed System, "Balanced Capacitive Matching." 
This new array promises to be the most universally accepted 
amateur beam ever developed for 20 meters. 



TAKE A LOOK AT THE VI'.AL STATISTICS ! 

FORWARD GAIN: 9.8 db compared to reference dipole; 

11.9 db over isotropic source. 
POWER RATED: 1 KW AM/CW; 2 KW P.E.P. SSB input to the 
SWR: 1.5/1 or better. 

MATCHING SYSTEM: Balanced Capacitive. 
FEED POINT IMPEDANCE: 52 ohms. 

NUMBER OF ELEMENTS: 5. Aluminum tubing; 6063-T832. 
MAXIMUM ELEMENT LENGTH: 38 ft, Vh in. 
BOOM LENGTH: 46 ft. 

RECOMMENDED MAST SIZE: 3 in. OD. 

TURNING RADIUS: 28 ft. 

WIND SURFACE: 18.7 sq. ft. 

WIND LOAD {EIA Std. 80 MPH): 364.45 lbs. 

ASSEMBLED WEIGHT: Approx. 139 lbs. 






final 



SHIPPING WEIGHT: Approx. 145 lbs. via truck. 
For detailed brochure write . . . Dept. 198G 




mWom/eu S&othcvS*. Ad 



my 



Manufacturing TV Antenna-Accessories 
for nearly a Quarter of a Century. 
Write for the Free Booklet. 

"How to Improve Your TV Picture" 

Department 198TV 
4610 N. LINDBERGH BLVD., BRIDCETON, MO. 63044 



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